Went to three job interviews and got declined because

Got interviewed thrice and got declined because i can't speak arabic even if it was stated in the job description that it was a "plus". They seemed impressed about my technical and english skills but doesn't matter anyway if i didn't make it. So my concern would be is that if i would learn arabic how long would it take to master it?while formal education would be great i'm afraid that the social dynamics would be hard to master. Like nuances on how to network and make friends. Tones and body language. Any tips?maybe someone who could mentor me?

It depends on your learning ability. Some take years to learn something which can be learn in months. I suggest you watch TV serials/soaps to learn about language and culture.