Bundle ID

I am being asked to enter a “bundle ID”, but find no information on how to do this. Can anyone help?

Your bundleID is something like this…
com.marioborelli.myapp
com.marioborelli.myapp1
com.marioborelli.myapp2
and it goes in the Bundle Identifier
Each app will have its own bundle ID
where my app, myapp1, myapp2 are their names.

Thank you !!