Once upon a time in the early 21st century, people used to say "You just got OWNED!" when someone was on the losing end of a fight, deal, game, etc.
Because of the close proximity of the "O" to the "P" on keyboards (and especially with the advent of texting) "Owned" eventually, morphed into "Pwned".
So here we are with a super helpful website called HaveIBeenPwned.com
When you enter your email address, the site searches for any websites you subscribed to with that email.
If one of those websites has had its data compromised, it notifies you of the name of the site and how extensive the data breach was.
For example: Dan was pwned three times and I was pwned twice.
What to do if your data is compromised
The site has a reference of excellent advice for what to do.
The advice usually boils down to changing your password for compromised sites.
If you use the same password for most of your accounts, you may want to change those as well.