I show users I don't recognize connected to my Time Capsule network

Hello all,

I'm suddenly seeing users I don't recognize listed under Shared in my finder window.

Does this mean that I have unauthorized people connected to my network?

Do they have access to my computer files, or my Time Capsule backups?

How to I get more information on them, and then ban them from my network?

I'm running a Time Capsule, 2 TB, flat square version, using it to connect a 2012 iMac, 2 MacBook Pros (8,1), 2 iPhones model "5s", and a first-generation iPad.

Thank you in advance for your help!

Tim