While this question may well encourage some form of debate benbenn, you should be aware that if you type your question into a search engine, you'll be provided with a comprehensive selection of answers.
what does CM,FM,IM,CWM,GM stand for?

IM = International Master
NM = National Master
CM = Candidate Msater
FM = FIDE Master
WFM = Womans FIDE Master
WCM = Womans Candidate Master
WNM = Womans National Master
WIM = Womans International Master
WGM = Womans GrandMaster
LM = Lichess Master
GM = Grandmaster

IM = International Master
NM = National Master
CM = Candidate Msater
FM = FIDE Master
WFM = Womans FIDE Master
WCM = Womans Candidate Master
WNM = Womans National Master
WIM = Womans International Master
WGM = Womans GrandMaster
LM = Lichess Master
GM = Grandmaster

GM=Garbage Master
FM=Fake Master
CM=Cheating Master
NM=Noob Master
FM : Fake Master
CWM: Completely worse master
ooferd
Loliputooferdthere.
Official Titles:
CM = Candidate Master
CWM > WCM
WCM = Woman Candidate Master
NM = National master
FM = FIDE Master
IM = International Master
GM = Grandmaster

GM=Garbage Master
FM=Fake Master
CM=Cheating Master
https://www.chess.com/blog/Joseph_Truelson/my-favorite-gm-win-washington-junior-open-round-4
You should discern quantum/quasi masters; they are the genuine fake ones with their pretentious quantum mechanical taste. For one, they don’t even know where their pieces are as they are constantly in a superposition of states, and having undergone some ten thousands of lectures on Bohr, they can’t be bothered to invest tedious time into this aggravating Bohring game. Until... they resort to game theory with the incredible Nash Equilibrium. But we shall leave that to the EMs, economics masters, to finalize their verdict, with their ostensible electromagnetic radiation and Poynting vector capabilities. Surreal stuff is seething out of somewhere in smooth seductive curves.

Does it mean that on chess.com if someone has written FM before his name in red box, that he is truly a Fide Master?

GM has long been understood as Global Menace, only in very recent history has it been known to mean Grand Master
CM - Cheese Master , FM - Flying Master IM - Independent Master GM - Giga Master . CWM - Cheese Woman Master

GM=Garbage Master
FM=Fake Master
CM=Cheating Master
NM=Noob Master
FM : Fake Master
CWM: Completely worse master
Haha yes the garbage master, master of the garbage
truly someone to be feared
GM=Garbage Master
FM=Fake Master
CM=Cheating Master
NM=Noob Master
FM : Fake Master
CWM: Completely worse master
It's WCM, so... Water Closet Master?