A comment is non-functional text in a script, which is ignored by KoLmafia when running the script. They are most commonly included to help someone reading/editing the script (including the script author!) to understand or navigate the script. Sometimes commands are "commented out" during debugging, to prevent them from being executed while testing.
It is generally considered good practice when writing a script to include a few comments explaining the purpose of various sections, especially to clarify any difficult-to-understand parts.
ASH has three different options for commenting -- the pound sign (#), the double forward slash (//), and the block comment (everything between /* and */). See the following example:
As far as KoLmafia is concerned when running the script, that entire example looks like this: