According to MMAJunkie:
Rousey plays Luna, an “athletic female bartender” in her 20s who joins up with the “Old Expendables” to battle one of their own.
Just like Rousey, Luna is quick with words and handy in a fight.
In all, the champ appears in over 20 scenes and has 35 lines of dialogue, though unsurprisingly, much of her job involves driving, flying, and shooting things.
While the script is a working draft – penned by husband-and-wife writing team Creighton Rothenberger and Katrin Benedikt, who wrote the recent action thriller “Olympus Has Fallen” – and is likely to be modified both before and during filming, it’s a big undertaking for Rousey, who’s never before acted in a feature film.