Hey there! NSFW means “Not Safe For Work” this is generally everything you wouldn’t want your parents or your boss to see. In this specific case it mainly aims at stuff that is considered 18+ such as nudity.
SCRATCH IS SO AWSOME YES I USE IT TO MAKE GAMES HERE MY ACCOUNT
https://scratch.mit.edu/users/BlueCupMakers/
ok srry yes you can use it to make a game. just use this scratch to html and if you every want to make the game downloadable (after the jam) then i suggest make it a zip. here: https://sheeptester.github.io/htmlifier/
EDIT: you ask too many questions but it ok ask as many as you want