Here are the classes, structs, unions and interfaces with brief descriptions:

Nsf
CAudioResource	Abstract base class for every class that owns a device-dependant resource – allow them to initialize / shutdown even when the audio context is not created
CClock	Clock is an utility class for manipulating time
CColor	Color is an utility class for manipulating 32-bits RGBA colors
CContext	Class wrapping an OpenGL context
CDrawable	Abstract base class for every object that can be drawn into a render window
CEvent	Event defines a system event and its parameters
CKeyEvent	Keyboard event parameters
CTextEvent	Text event parameters
CMouseMoveEvent	Mouse move event parameters
CMouseButtonEvent	Mouse buttons events parameters
CMouseWheelEvent	Mouse wheel events parameters
CJoyMoveEvent	Joystick axis move event parameters
CJoyButtonEvent	Joystick buttons events parameters
CSizeEvent	Size events parameters
CFont	Font is the low-level class for loading and manipulating character fonts
CFtp	This class provides methods for manipulating the FTP protocol (described in RFC 959)
CResponse	This class wraps a FTP response, which is basically :
CDirectoryResponse	Specialization of FTP response returning a directory
CListingResponse	Specialization of FTP response returning a filename lisiting
CGlyph	Structure describing a glyph (a visual character)
CHttp	This class provides methods for manipulating the HTTP protocol (described in RFC 1945)
CRequest	This class wraps an HTTP request, which is basically :
CResponse	This class wraps an HTTP response, which is basically :
CImage	Image is the low-level class for loading and manipulating images
CInput	Input handles real-time input from keyboard and mouse
CIPAddress	IPAddress provides easy manipulation of IP v4 addresses
CListener	Listener is a global interface for defining the audio listener properties ; the audio listener is the point in the scene from where all the sounds are heard
CLock	Lock is an exception-safe automatic wrapper for locking and unlocking mutexes
CMatrix3	Utility class to manipulate 3x3 matrices representing 2D transformations
CMusic	Music defines a big sound played using streaming, so usually what we call a music :)
CMutex	Mutex defines a mutex (MUTual EXclusion) object, that allows a thread to lock critical instructions to avoid simultaneous access with other threads
CNonCopyable	Utility base class to easily declare non-copyable classes
CPacket	Packet wraps data to send / to receive through the network
CPostFX	PostFX is used to apply a post effect to a window
CRandomizer	Randomizer is an utility class for generating pseudo-random numbers
CRect	Rect is an utility class for manipulating rectangles
CRenderTarget	Base class for all render targets (window, image, ...)
CRenderWindow	Simple wrapper for sf::Window that allows easy 2D rendering
CResource	Base class for every resource that needs to notify dependent classes about its destruction
CResourcePtr	Safe pointer to a T resource (inheriting from sf::Resource<T>), its pointer is automatically reseted when the resource is destroyed
CSelector	Selector allow reading from multiple sockets without blocking
CSelectorBase	Private base class for selectors
CShape	Shape defines a drawable convex shape ; it also defines helper functions to draw simple shapes like lines, rectangles, circles, etc
CSocketHelper	This class defines helper functions to do all the non-portable socket stuff
CSocketTCP	SocketTCP wraps a socket using TCP protocol to send data safely (but a bit slower)
CSocketUDP	SocketUDP wraps a socket using UDP protocol to send data fastly (but with less safety)
CSound	Sound defines the properties of a sound such as position, volume, pitch, etc
CSoundBuffer	SoundBuffer is the low-level for loading and manipulating sound buffers
CSoundBufferRecorder	Specialized SoundRecorder which saves the captured audio data into a sound buffer
CSoundRecorder	SoundRecorder is an interface for capturing sound data, it is meant to be used as a base class
CSoundStream	SoundStream is a streamed sound, ie samples are acquired while the sound is playing
CChunk	Structure defining a chunk of audio data to stream
CSprite	Sprite defines a sprite : texture, transformations, color, and draw on screen
CString	String defines a graphical 2D text, that can be drawn on screen
CThread	Thread defines an easy way to manipulate a thread
CUnicode	Provides utility functions to convert from and to any unicode and ASCII encoding
CText	This class is an abstract definition of a unicode text, it can be converted from and to any kind of string and encoding
CVector2	Vector2 is an utility class for manipulating 2 dimensional vectors
CVector3	Vector3 is an utility class for manipulating 3 dimensional vectors
CVideoMode	VideoMode defines a video mode (width, height, bpp, frequency) and provides static functions for getting modes supported by the display device
CView	This class defines a view (position, size, etc.) ; you can consider it as a 2D camera
CWindow	Window is a rendering window ; it can create a new window or connect to an existing one
CWindowListener	Base class for classes that want to receive events from a window (for internal use only)
CWindowSettings	Structure defining the creation settings of windows