Meaning of I OWE YOU ONE - A Really Short English Lesson with Subtitles

So in English when we say "I owe you one" it means that someone has done you a favour

and what you're saying to them is next time you need help I'll be willing to help you.

So a good example would be let's say you're moving.

You've found a new apartment or a new house to live in and a friend of yours comes and

helps you move, helps you get all of your stuff from your old place to your new place.

When you're done moving all of your stuff you would say to them "I owe you one."

which means the next time you need a favour, the next time you need help you can call me

because I'm recognizing the fact that I owe you one.

I owe you a debt.

I owe you a favour.