All EF 50mm f/1.8 lenses are excellent for any Canon camera; they're inexpensive and reasonably sharp. Which one will you be getting, the current STM version or the discontinued Mk II one?

Most likely the current STM version.

Good choice. 50mm on a crop sensor camera is a bit limiting as its field of view is narrower than the same lens mounted on a full frame body, but the EF 50mm f/1.8 models are the least expensive prime lenses in the Canon lineup.

If you're on a budget but wish to try wider primes with your SL2, I would gently suggest the affordable EF-S 24mm f/2.8 STM pancake lens too. :o)