Ratings and reviews
Ratings are the one-to-five stars people give your app in the store; reviews are the ratings that come with written words.
Also called App Store rating, Star rating.
In plain words
Someone in Canada gave Fern 5 stars: "Finally remembered to water my monstera."
How Apparent would say it about Fern, an example app in the live demo.
Good to know
Your rating shows next to your app everywhere it appears, so it affects how many people download it. Most ratings come from a prompt inside the app, so when you ask matters.
Reviews are the cheapest research you'll get: real people telling you what they love and what broke. A sudden run of one-star reviews after a release usually points at a bug.
Both stores let you reply to reviews, and people can update their rating after you do.
Where the number comes from
App Store Connect and Google Play Console.