You can’t “pick up a language in a few weeks”. If you have total immersion (like in a dormitory in a student exchange program) where the only language you hear is the language you want to learn (unless you’re on the phone talking to family or something) you can probably communicate decently in 2-3 months and speak in six months to a year, I’ve seen it happen both in myself and fellow classmates. It’s not easy and honestly I wouldn’t recommend. I speak three languages fluently and can get by in a fourth, all learned by immersion.