To get the list of all the variables or functions that have been declared and pre-existing:
ls variable:*
ls function:*
Note: You can change the wildcard(*) if you are looking for something more specific.
ls can obviously be substituted with dir or get-childitem if you are more familiar with those key-words.
Something Interesting:
If you want to look more closely at what the function is actually doing then you just need to type: $function:<name of function> like so:
$function:mkdir
which will return:
param([string] $name) New-Item $name -type directory
