As I read it, it amends paragraph 501(3)(h) of the Criminal Code to add the words “firearm part”.
For a bit of context, that section provides a police officer who has arrested somebody with the ability to release that person on what's called an undertaking. As set out in that section of the Criminal Code, an undertaking can include a number of conditions, one of which is to not possess a firearm. This would add “firearm part” to that condition, so a person arrested with a relevant offence could be released on an undertaking provided they agree to the condition not to possess firearm parts.