Hi Mariann!
How long does it tale to learn a language? Well, it depends.
What do you mean by "learn"? Are you thinking about just being able to make yourself understood in basic situations - perhaps the kind of language a tourist needs - or are you preparing to use the language for work or study?
Most research shows that it takes about 100 hours of focused attention (study, class or conversation) before native speakers notice a significant improvement in your ability to communicate.
So hours are hours. How long will it take you? That depends on how many hours a week you can devote to language.
If you spend 10 hours a week, you can make a big difference in your communication in just 10 weeks.
How long to become near native or "fluent"? Different people have different expectations of what fluent means.
Personally, I define fluent as " the level of language that allows you to participate in life -work, study or leisure - with native speakers in their community."
In order to become "fluent" you would probably need about 3 years of full time study, longer if you can only focus on language part time.
The key to improving your language is really spending time talking with native speakers who will meet you at your level of ability.
That's why I love italki!!!