You just try it yourself and go down the different lines. "Okay, Stockfish suggests this, but I wanted to do that, let's try my idea, oh, I didn't think of that response to my move". Etc., play along some lines, think about them. Sometimes it's obvious, other times it just sets up something far in the future you must be a grandmaster to see the subtlety of.

99.5% of the time you can understand it (percentage varies with rating).

Stockfish has created entirely new lines in chess which people incorporate into their play. For instance an early pawn push to h4 is now common among chess pros. It's value was not recognized before Stockfish.

Because then you explore the line and try to learn what is so good about the move

For some reason this question reminds me of all of the drama about Navier-Stokes from the last few days. Tangential to the ethical questions are tons of examples where in history when word gets out about a solution to a problem, not even the solution itself just rumors that there is a solution, suddenly competing solutions appear.

So maybe it matters like that? Just knowing that an oracle like stockfish is saying "this is the best move" may trigger pathways in your brain that promote understanding?