That adjusts speed, not acceleration. Tweak Tool is indeed what’s needed, but it’s not apparent to a newbie. I spent hours finding that particular app when I first used Ubuntu. It’s absurd that that kind of functionality isn’t built in.

I thought that was a acceleration.

Perhaps they'd not know of gnome tweaks, though they could remember Power Tools from Windows....

Mouse speed is how far the cursor moves for some distance of physical mouse movement. Mouse acceleration additionally makes the cursor's speed increase when the mouse's acceleration (change of speed over time) is faster.

Mouse acceleration is annoying (bordering on infuriating, imo) because it changes cursor movement from an easy 1:1 mapping of mouse movement->cursor movement by adding an additional dimension. You then not only have to keep in mind how far you're moving your mouse, but also how quickly you're moving it. I can't fathom why UI designers seem to think that it's so great that it should be present with no ability to disable it.