What does the title mean? At least I don't know

I don't know what MMF 2019 means in this context, but Bronycon was the title of a convention for My Little Pony fans, the series which is the source of several of these characters.

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@OP
First of all: not MMF, but MFF. You can see it by yourself in the filenames starting with "MFF_2019_". The gallery name is in error here.

Secondly, MFF is Midwest FurFest - world's largest furry convention, held in Rosemont, Illinois.

Finally, Willy2^10 is on point here - BronyCon is convention of "bronies", which is a term for adult male (usually) MLP:FiM (usually) fans. While sometimes used as an umbrella term to describe all the FiM fandom (or all the adult MLP fans in general), the term for female affiliates was "pegasisters", if I'm not mistaken.

EDIT: Here, have some wiki - https://ouo.io/uczXCD

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