i think it depends on context but the expression "~것 같다" could be "guess" or "impression on something you've got". for your guess, 비가 올것 같다 it's gonna be raining. 그가 파티에 올것 같다 i guess he's gonna come to the party. i guess he might come to the party. for impression on something, 내생각어때? what do you think about my idea on that? 음...좋은것 같은데.. well, it seems to be a good idea. 그래? really? 응 모든 문제가 해결된것 같아. it seems as if all problems are solved. :)

"~것 같아" = :"It seems ~", "It is likely ~" "~인 것 같아" = "It seems to be ~" "~할 것 같아" = "It seems that~",

것같아 normaly means 'maybe or I think' but it's not complete. if you show me whole sentence or phrase, then I'll explain for you more easily.