These links should explain why multiple Edge processes are running on the system.
Microsoft Edge’s multi-process architecture - Microsoft Edge Blog Improving how Microsoft Edge processes appear in Task Manager - Microsoft Edge Blog
Regarding the Explorer.exe processes, one Explorer.exe will be running anyway though you may not have any folder windows open. It's the default shell process.
The other Explorer.exe process may be a remnant process for a folder window launched earlier -- especially by running explorer.exe <folder path> or via a shortcut. The 2nd explorer.exe process may show up with the "/factory" command line argument.