Navigation, easily. I can learn a few basic phrases of a language, and odds are someone will speak English in the places I’m going. I can ask English-speaking people what the essential customs and etiquette are.
But if I don’t know where I’m going, I can’t be confident in what I’m doing. If I’m in a new place and have to follow a narrow set of directions to get to specific places, I’m confined to those narrow spaces. Knowing where I am and what’s around me opens up the world with me driving the experience instead of relying on the knowledge of others.
In both of the cities I’ve lived in, I hear a place mentioned and I instantly can point in its direction, estimate the distance, and calculate a good route to get close to there. At the music festival I’ve attended several times with a large venue I am the guy that people stop and ask for directions because I exude confidence in where I am. To be able to carry that knowledge with me anywhere in the world would be incredible.
And if “understanding the streets” includes knowing good restaurants or places to visit and whether a tourist would be welcome there, then all the better.