What is the meaning of IM, FM, CM and is that true there is SGM? (Super Grand Master)

IM = International Master, need to have had FIDE rating above 2400, plus have scored three IM norms.

FM = FIDE Master, need to have had rating above 2300,

CM = Candidate Master, need to have had rating above 2200.

There is no SGM, but there is GM (sometimes called IGM, International Grandmaster). You need 2500+ and three norms.