Here is an overview of the game from Nintendo:

A new adventure awaits you in this second installment of the turn-based RPG series set in the world of Monster Hunter! Become a Rider and form bonds with friendly monsters known as Monsties to fight alongside them as you take part in an epic story.
You play as the grandson of Red, a legendary Rider. The story begins with a fateful encounter with Ena, a Wyverian girl who has been entrusted with an egg with the potential to hatch into a legendary Rathalos which could wreak havoc if awakened to its destructive power.
Embark on a journey which will test the bonds of friendship in a changing world, and discover the truth behind the legends of old.

Check out the gameplay video below: