What is the meaning when someone say "He s really something?" What does "something mean?" Sorry for my bad english thanks?

"He is really something" means he is very remarkable or outstanding, regardless if it is good or bad.

Remarkable in some way. It might be good or bad. The something might be that he is obnoxious or it might be that he is talented or attractive.

It means he is remarkable or notable. It is ambiguous - can mean is something good or something bad.

It means that the speaker views him as being a person somehow apart from the ordinary. It is generally a compliment but can also be a form of "back-handed" compliment: a form of insult.

It differentiates somebody as being special and is opposite to "He is nothing." meaning that he is not special.