There is no native fm radio app. If the app Radio FM is on your iPad, and you didn’t put it there, that means you have not set the iPad up properly.
When you turned on your iPad for the first time you should have gone through a series of setup screens. You would have been asked to either give your current Apple ID, or create a new one. If you did not do this, then you are using an iPad still associated with the previous user’s Apple ID. Not a good idea for many reasons.
If you are talking about the Radio tab in the Music app, then depending on your status as a Apple Music subscirber you can see internet re-broadcast radio stations (see below) and/or Apple music stations (which may be hand currated, automatically generate, or a combination thereof).
There are several apps in the App Store that will let you listen to FM radio stations. However, you are not listening to actual radio. You are listening to an internet re-broadcast of that station. The down side; you can’t listen without an internet connection. The up side, you can listen to a rediculous number of radio stations from around the world.
My prefered app for this is TuneIn Radio; though I rarely use it. I believe it (and several similar apps) is also available on Android.
Another interesting not-real-radio app catagory is radio scanners. There are quite a few apps that will let you listen into local emergency service radio stations; Police, Fire, EMS, etc. The one I use is Police Scanner+