Question

analogy
rhetorical question
hyperbole
repetition
\learning to play the piano is like learning to ride a bike. at first, its difficult and frustrating, but once you get the hang of it, it becomes second nature.\
(rhetorical device)

Explanation:

The sentence compares learning to play the piano with learning to ride a bike, which is the definition of an analogy (drawing a comparison between two things to explain or clarify). Rhetorical Question is a question not seeking an answer, Repetition is repeating words/phrases, and Hyperbole is an exaggeration—none of these match. So the rhetorical device here is Analogy.

Answer:

Analogy