What does the Spanish word or phrase MM mean?

"MM" in Spanish doesn't have a commonly recognized meaning. It's possible you are thinking of something else, or it's a specific slang or abbreviation used in a particular context.

Could you please provide more context?

For example:

* Where did you see "MM" used? (e.g., on a website, in a text message, on a sign)

* What was the surrounding text or conversation?

* What do you think it might mean?

Knowing more about the situation will help me understand what "MM" might refer to.