remap is an option that makes mappings work recursively. 
By default it is on and I'd recommend you leave it that way. 
The rest are mapping commands, described below:

:map and :noremap are recursive and non-recursive versions of the various 
mapping commands. For example, if we run:

:map j gg           (moves cursor to first line)
:map Q j            (moves cursor to first line)
:noremap W j        (moves cursor down one line)