peel 1- [uncountable, countable] the thick outer layer of some fruits and vegetables orange/lemon peel (North American English also) an orange/a lemon peel
2- peels North American English(also peelings British and North American English) [plural] the skin of fruit or vegetables that has been removed
This is what I think
So if we refer to the whole outer layer of a banana in general then say “a banana peel”, for example, "you need a banana peel to treat your acne"
but if we already removed the skin of that banana, then we say “the peels of the banana”
For example, "the above picture shows 4 peels of a banana".
Is that correct?