One possibility, and that which I understood as an event, is an event. As you see, every level contains a lot of events, so perhaps he meant any kind of character, pickup, etc. like Lizard, Apple, new kind of Gem. Yeah, inventing new kind of an event, so I thought if there were 18 new events, they could be useful for future levels...

Ok ok, just ignore that what I wrote there. It was a stupid and weird thought but there's still a little chance he meant something like that. I actually just nominated that.