How? They quickly switch to a common language or avoid the situation entirely. When traveling, (only few concepts are required for tourists and workers) most concepts are easier to show by hand and foot than to be learned in the visited language. Even if they learned something during the visit, it’s about <0.1% of that language. Because adults share so many concepts already, they quickly understand and don’t even need to learn all the words and grammar to get around. So adult migrants immerse differently than children who still learn new concepts.
Adults hardly get into that situation.
Actually, that’s not true at all. Adults regularly have multiple roommates that speak multiple languages.
How? They quickly switch to a common language or avoid the situation entirely. When traveling, (only few concepts are required for tourists and workers) most concepts are easier to show by hand and foot than to be learned in the visited language. Even if they learned something during the visit, it’s about <0.1% of that language. Because adults share so many concepts already, they quickly understand and don’t even need to learn all the words and grammar to get around. So adult migrants immerse differently than children who still learn new concepts.