Friendship is composed of a single soul inhabiting two bodies.

The closest friendships stop needing translation. You have shared enough that the other person can follow half a sentence, predict your reaction and hear when the cheerful voice is a cover, so the whole exchange runs on far less explanation than usual. That kind of understanding is built rather than found, and the building is mostly hours. Two people, one accumulated store of context.

If you want that with someone, the only real ingredient is time spent without an agenda. Ordinary time, not milestone occasions. And if you already have it with someone you have been too busy for, protect it before the shared context quietly goes out of date.