There's not enough information provided to be certain. Funimation has a history of dealing with anime, so it's possible that Funimation Monster Hunter Stories is an anime adaptation of the Monster Hunter franchise. But considering how popular Monster Hunter games are, it could also be a new game in the series with some sort of Funimation branding or collaboration. It might even be a hybrid project that combines elements of both an anime and a game, such as an anime - inspired game or a game - inspired anime.
Funimation Monster Hunter Stories is mainly about the Monster Hunter world in a story - driven format. It likely involves adventures, hunting monsters, and building relationships with various monsters as in the Monster Hunter franchise.
The Hunter x Hunter manga is unfortunately not complete. The author has faced various issues that have led to intermittent breaks and an unresolved storyline.