> no Questions That Don't Deserve Their Own Thread (QTDDTOT)
So here it is now. As for this Question That Didn't Deserve Its Own Thread:

What do you call it, when you press hold a letter or number on your physical keyboard, that determines how fast that number or letter gets "auto-typed" and how short the delay is before inserting said character?

I'm using Fluxbox on MX Linux, and I don't know what that setting is called, meaning I don't even know what man page or setting/system application's called that's buried somewhere to look up and RTFM.

If it matters: here's the neofetch for this 11-yo PC which hasn't been updated for several years. It doesn't say which exact version of Fluxbox and which exact version of MX is being used, don't know which exact key terms to web-search to find out how to show that info, and it's likely irrelevant.