-것 같다 [ -geot gatda ]

같다 means usually ‘to be the same’. Polite forms are 같아요 [gatayo] or 같습니다 [gatseumnida].

ex)

너와 나는 나이가 같다.  (You and me are at the same age.)

우리는 취미가 같아요.  (We have the same hobby.)

However, -것 같다 is used to depict uncertainty or speaker’s guess. It is similar to the English expression ‘it seems -‘ or ‘I think -‘.

This expression usually comes after a verb or adjective, which ends with -ㄴ/는 for past or present and with -ㄹ/을 for future.

ex)

나 아픈 것 같아. (I think I am sick.)

눈이 온 것 같아요.  (It seems it snowed.)

그가 올 것 같아요. (It seems he will come soon.)

그는 착한 것 같아요. (I think he is kind.) — the speaker probably had chances to see his kindness.

그는 착할 것 같아요. (I think he is kind.): the speaker does not know him very well or possibly saw him for the first time.