My 6 year old has been watching 20 minutes of cartoons every night for the past two years. This is the only exposure to the English language that she has ever had.

She has learned to understand what is said in the cartoons. Of course she misses some things, but it's surprising how much she gets.

Like, when I ask her "what did Bluey just say?", she can explain it.

Children's brains are awesome.

But actually, grown-ups can also pick up quite a lot if they actually immerse themselves.