Acrylic paint can be used on most surfaces as long as it is primed, or has the appropriate additive mixed in with it. The most common surfaces for acrylic paint however is canvas.
Stretched canvas is stretched over wooden bars and comes in standard depth and deeper 3d canvas which are popular because you can paint the edges and they don't need a frame.
Canvas boards are canvas laminated onto a board and are much more economical than stretched canvas if you are just starting out. They are also a lot less bulky if space is an issue for you.
Canvas pads are loose sheets of real canvas bound together in a pad.
Acrylic paper is textured paper with a special coating designed to be used with acrylic paints. It comes in loose sheets or pads and is great for practicing.