To create single-line comments, begin a line with the character #. Windows PowerShell does not support multi-line comments, but it is possible to deactivate larger regions of your script by placing them in a here string:

# This is a regular comment

# Start of the here string
$null = @"
function MyTest
{
       "This should not be considered a function"
}

$myVariable = 10;
"@
# End of the here string

# This is regular script again