Question

You also learn what it takes to make money: a lot of effort.

What is the verb in this sentence?
O money
O you
O effort
learn

Answer 1

In this sentence, the verb is probably learn.

Answer 2

In this sentence :
"You also learn what it takes to make money: a lot of effort.”
The main verb is "learn". The verb Takes is also a verb but since it is within the next clause and it is the verb of the Cataphoric refrence "it" such verb cannot be considered the main verb of the sentence.
So your final aswer is Learn.