"Hey, no one's perfect when they start, and we'll both be beginners." Sure, he might know the basics of volleyball, but does she? Regardless- "I always want people to learn new games! I got a pal, Romeo, I know he'll be up for a game. And I'll bring along some more friends--you should too!"

He nods upon saying that, and a way to make sure he isn't just including a bunch of strangers, and she can has people she knows around too. Though, even if she comes along alone, he knows his friends would make her feel welcome. And Romeo will be a good kid to her.