[ask_b123]

Is S = command?

What I'm seeing is: close a tab -> cmd+w; copy something -> cmd+c; switch tab -> cmd+option+left/right arrow, switch window -> cmd + `

[umanwizard]

Yes, coutego is using Emacs notation for key chords, in which S-whatever means what macOS users would call cmd+whatever, Windows users would call win+whatever, etc. "S" stands for "Super" key.