It can be defined as one of the most popular open-source libraries for .NET and it allows developers to validate their models or business objects using strongly-typed validation rules and It makes validation code clean, easy to understand, and easy to maintain because the validation code is not tightly coupled with the models and is generally written separately.

@padmakeechu can you please tell me how to Configure FluentValidation in ASP.NET Core, Create a Model and Creating a first Validator Data Input Form also ?

Sure , you just go through this link where it can be very useful to you to understand.
https://www.ezzylearning.net/tutorial/asp-net-core-data-validations-with-fluentvalidation?fbclid=IwAR3dmfJHEkEb_XjgVpbZAEGfqN0PnPnurYylQr5-ebMal4P_FYIwSuG8Ylg

Great, thank you for sharing.