One of the funniest (and obscure) VIM features is repetition counter. Most of the commands allow the counter. Consider example (that needs to be typed in in normal mode):
The VIM's command 'l' is the command to move left (VIM supports motion keys as in old time games - 'h', 'j', 'k' and 'l' are correspondently left, down, up and right.) Prepended to it '20' is the repetition counter. If cursor was in position 1, after the command it would be in position 21 (or on end of line if it is shorter).
Would delete 1000 lines starting from current.
Would move cursor to third space in line, counting from current cursor position. (
:help ffor find motion command.)
It is very useful at times for example combined with command '.' which is used to repeat last command(s). Example how to make a nice C comment with 50 dashes.
I intentionally made typing of dash separate, thus it can be later repeated with '.' command. I yet to gain complete understanding on how '.' works precisely, but in most obvious cases it works as expected.
:help .for more info. Experimentation plus 'u' undo command could help to get it right.
More info can be found in VIM under