Every language has words that are almost the same sounds but not quite.

English speakers barely pronounce can and can’t differently. If you’re in a noisy place, or are not familiar with the accent of the speaker or got a flu and your ears are blocked or whatever else, you’ll have an extra bad time telling them apart. That’s normal. Just extra annoying that this particular example involves a particular meaning and the opposite of it, so context is not your friend.

HEY MATE, CAN YOU PLEASE COME TO THE PARTY?

I CA’!±:-

OH COOL

I SAID I CA;(++;:-

OH SO YOU CAN’T? YEAH?

YEAH! THAT’S WHAT I SAID.

WELL YOUR LOSS

I SAID I WILL COME, DUDE

OH SHOOT. OK. SEE YOU THERE.