I read a headline on the internet once (in other words: What I'm about to say is almost certainly bullshit) that cat owners can understand THEIR OWN cats.

Anecdotally as a cat owner, it seems we train each other, cat makes a noise to get attention, human gives a kind of attention when hearing that noise, cat starts making that noise to get that specific attention. My cat has a food meow, an attention meow, a bath water meow (my cat likes to drink from the tub faucet) and a "it's 3 AM and my brain can't handle it" meow, and I can definitely tell them apart. There's also a difference between the "enjoying a shoulder rub" purr and the "make me breakfast make me breakfast make me breakfast make me breakfast" purr. Hand me a different cat and that cat speaks mandarin Swahili.