On finder menu, what is "network" under locations and why is there something that looks like a PC?

My iCloud is suddenly reloading and re-setting up on my iMac. No idea why. Im looking around my iMac on finder and noticed under Locations there is a Network which when clicked shows up as a PC. How to identify what it is and delete it? But more importantly, why is my iCloud suddenly gone and reinstalling itself on my iMac for no apparent reason? is my iMac compromised?