How do you read "y/n" when you see it out there?

I read it as Yes/No on forms etc.

It's not yes or no?

Quote from xoxoshawol

It's meant to your own name when it's written in fanfictions

fanfics? OHH!

Depends on the context, for forms I read it as Yes or No, for fanfic it's your name.

Math, Y divided by N.