"I think the project is (really) something." This is really casual. You asked: well, I mean does the word "something" mean "a big deal", and what's its usage? I don't think it means "a big deal". The examples below might help. vvv Examples: "This is really something!" "This food is really something!" "something" -> great, exciting, surprising, etc. "That girl is really something." In this case "something" can be more negative. something -> strange, crazy, etc. You can also add "else" at the end. "That girl is really something else." [I personally add "really" when I want to say "... is (really) something!"] So, "something (else)" can be used for different things, but it's definitely not right for formal setting (class, work, etc.). I would advise using it only with friends.

Do you mean: I think that the project is something? If so, you need to add more details. Example: I think that the project is something big/incredible/fantastic/out of this world etc. That way you let people know that the project is a big deal and very important.

i can't understand your point? what were you trying to say?

No, it is not. And I don't even know what you are trying to say.