Catch on and Have

Catch on verb - Understand, usually after some initial difficulty.

Have and catch on are semantically related. in appreciate topic. In some cases you can use "Have" instead a verb "Catch on", when it comes to topics like understand.

Have verb - To keep, control, or experience as one's own.

Catch on and have are semantically related. Sometimes you can use "Catch on" instead a verb "Have".