I saw it on this website and I liked the shirt they're wearing, the black top thing that shows a bit of cleavage. what is it called?

You can try cut out bodysuits. Here's some similar ones here:

Look up cut outs

Nylon mesh, openwork, sheer - there's a few keywords. Good luck!

v-neck? i think

Sheer / chiffon tops

Wait what was the question again? Seemed to have lost my trail of thought..