If she is just interested in getting started and trying things out, I would suggest either getting her a trainer kite or getting her lessons.
She will need a trainer kite, which is a small scaled-down version of a power kite. She can safely use it to learn the skills she will need to fly a bigger power kite, and it is fun at the same time. OR makes a real nice Rise Trainer that could end up doubling as a high wind land kite. Unlike most trainers, the OR Rise is an inflatable!
Getting her lessons is another good option. In one session of lessons she’ll get to learn about the sport, fly a trainer, fly a full-size power kite with an instructor, and potentially get her first session in the water.
If you do end up buying a full size power kite, most women start of with something in the 8 or 9m range. In my honest opinion, and other might disagree, you’d be better off spending your money first on a trainer and/or lessons. That way she can get a taste of it before you plunge headfirst into it.