A rate limit is a cap on how many requests a service will accept in a certain period. A service may also limit how much information can be processed during that time.
Imagine a small gate that lets a steady flow of people through. If too many arrive at once, some may need to wait and try again later. Online services use limits to manage demand and keep systems available.
If an app reaches a limit, it should respond sensibly, such as waiting briefly before trying again. A rate limit is not necessarily a sign that the request itself is wrong.