This is a pair of Manfrotto triple hooks, these either go onto a wall (which is how I used them) or you can use special clamps to clamp them onto vertical poles for more mobile background support systems.

I should make it clear, all I have are these two triple hooks, I don’t have any clamps or any other type of fixings.

They are used to put back drops on, so you can either do chroma keying (where you photograph or video someone or something in front of a blue or green background and then use software to make the background disappear and you can then insert your subject into any photo or video scene you like) or there are hundreds of different coloured or themed backgrounds you can place your subject in front of and video or photograph them, which is what most professional portrait photographers use them for.