What does the arrow with 2 lines through it mean?
Solution 1:
That is the page or scroll up key. On a MacBook the keystroke is Fn-Up Arrow.
“What Do the ⌘, ⇧, ⌥, ⌃, ⎋, ↩, ⇥, ↖ and ↘ Menu Symbols Mean?”
Each symbol corresponds to a key on your keyboard:
⌘ — Command/Apple key
⇧ — Shift key
⌥ — Option/Alt key
⌃ — Control key
↩ — Return key
⇥ — Tab key
⎋ — Escape key
↖ — Home key (Function-Left Arrow on laptops)
↘ — End key (Function-Right Arrow on laptops)
There is a very handy reference at harvard.edu.