So long as the disks are not set as “independent” they will be included in your snapshot.
A snapshot is a point in time state of the VM that you have the option of reverting to if you want to.
The typical administrator use is to take a snapshot, make some change to the VM OS/applications/data that you think you might want to undo, delete the snapshot of you don’t need to revert the VM state back to the point where you took the snapshot.
They are also used temporarily by VM backup tools to have a consistent state while allowing the VM to continue to run, snapshots taken by backup tools are deleted by those tools at the end of a backup process.
What is your use case for wanting to use snapshots?