if someone says...what do you think that means.......?

Hmm... to me, it sounds like the person has some sort of affection or feelings for you and is giving u a subtle hint that he/she does. Thus, he/she may want you to make the first move. lol, not sure, just my speculation. Good luck and take care. :)
If he smiled when he told you that he couldn't reveal his feelings, lol, it sounds so likely that he likes you. :)

It sounds to me that this person can't tell you because of one of two reasons

1) they themselves dont actually know how or if they feel anything for you OR

2) The feelings they have are so intense for you words could never begin to express the depth