One of the meanings of "pick up" is: - to learn a new skill or start a habit without intending to e.g. She picked up a few German phrases while staying in Berlin. source: https://www.macmillandictionary.com/dictionary/american/pick-up#pick-up__17

"Pick up" is one of those phrases that can have different meanings in different contexts. Yes, it can mean acquiring knowledge or skills without specifically studying how to do it just from exposure and seeing or hearing. Most literal picking up is deliberate, but can be accidental like a horse picking up a stone in its hoof. That may be the origin of that usage, that something just clings to you by being in contact with it.

Thanks Lisette Alejandro for your good explanation. I hope I picked up everything you said :)

In this case it helps to think of absorb. If you spill water and you wipe it with a napkin.. the napkin will absorb the water (Pick up the water) and take it. If you pick up a language well... it means you are good at learning languages... a good language learner.

Thanks Nahuel. The link below given by Alice contain more or less exhaustive explanations of this phrase https://www.macmillandictionary.com/dictionary/american/pick-up#pick-up__17