How do you say this in English (US)? What is the difference between flap , flip , and flop ?

See a translation

Flap: among all the meanings this word has, it can stand for
A. 'To wave something (a bird flaps its wings)'
B. Informal speech: 'behaving nervously or really happy'
C. Part of cloth, carton, etc which connects to the, usually bigger, rest of the material. Often used to close or open, like a classic door.

Flip: it always has a feel of turning, something fast, and change
A. 'I flipped the coin to see the number'
B. To jump and then turn completely, like gymnasts
C. To sell a property right after buying it

Flop: has a feel of clumsiness
A. To fall
B. (for a movie, book) To be unsuccessful
C. A failure, to fail

I hope this helps

A pleasure :)