"I want to improve my Swedish."
Translation:Jag vill förbättra min svenska.
Vem kan förklara mig nånting? Varför säger-skriver man "min svenska", när "språk" är ett-ord? Varför inte "mitt svenska"? Tack på förhand!
"Språk" itself is an ett word, but specific languages are "en" words.
"Min svenska, din tyska" etc
I thought it would make sense to say either mina svenska eller min svensk?
You're thinking of the adjectives. I was using the nouns "Svenska/Tyska", which refer to the languages themselves, instead of things that are "Svenska/Tyska".
However, even as an adjective, you couldn't say "Min svensk".
Possessive pronouns always take the definite form of adjectives, so you would always say "Min svenska [noun]", "Ditt tyska [noun]", etc, and never "Min svensk", "Ditt svenskt".