Sluggar,,,,,,, Swedes often using "ar" in the end of words,,,,, i think its a plural thing. ( me not really getting grammar in any language, even my native Danish )
Just google translated it, and it seem if you translate sluggar from Swedish to English you do get slugs
Pluggar i do know with my Swedish knowledge mean plugs, where as i think plugga is to work hard / study hard.
I dont really know why i " master " Swedish, it is after all a Troll language, spoken by people living in caves under mountains,
I have only gone fishing up there for salmon a few times, but it probably date back to my youth where i did read the Swedish car magazine called Bilsport, as there was no such magazine in the hellhole ( Denmark ) i am born in.
And after all Danish / Swedish / Norwegian are not terrible different languages, at least not for natives.