Hi Launchers are the main interface you see when you turn the phone on.
I used Nova Launcher to get rid of the Google search bar for example.
Here’s a topic on Launchers It’s an old topic and only really useful to give an indication of how many there are and what they do.
For example the content about Nova Launcher may have been true a long time ago but it was ‘perfectly’ fine with my FP3 using Android 10 and now 11.