W2S Question

So i was coding my cheat and i thought to start to make an esp i asked some friends and they told me about the w2s thing but i couldn't understand, so can someone explain me?

how does it works.
what do i need to do.
and if i need offsets which one?
Ps: i don't know if that matters but my cheat is external.
i never did a esp before so if you have patience to explain me i would be grateful

it transforms entitys world position to the screen position, otherwise youd just get some kid of a radar. unless youre going for an overlay, its not needed.