Same mailbox split into 2 separate folders

Hello,

I have one Google Mail IMAP mailbox that I added to Apple Mail on Mac OS Sonoma 14.2.1. When I open in Finder the directory /Users/USERNAME/Library/Mail/V10/ I can see for this same mailbox 2 folders marked in red:

In the 2nd folder are the files Outbox.mbox and SendLater.mbox which I cannot see in Apple Mail itself. For what are these files used, are they needed and can I move them to my other folder for the same mailbox or will something break?

I have searched now a lot but cannot find these answers.

Thank you,

Philip