Sort of has two meanings.
It can mean similar to, as explained by marg93. In this case we add 'like' so we can say one thing is 'sort of like' another thing. Meaning that it is similar, but not a close similarity.
Grading similarity would be: identical, similar, quite like, sort of like, not very like, dissimilar.
The second meaning is a vague response, usually to questions about personal likes and dislikes, where you don't have a strong opinion.
Example question: Do you like sport?
Possible answers: Yes, I love it; Yes, I enjoy it; Sort of; Not much; Not at all.
Hope this helps