A Disexual person (Sometimes known as Dyosexual) is someone who is attracted to exclusively 2 genders. These genders can be any 2 genders, if you're exclusively attracted to 2 genders you're allowed to use the label Disexual/Dyosexual.
It's very similar to Bisexual, but is not the same. Bisexual is
attraction to 2 or more genders, while Disexual is
attraction to only 2 genders. You can still use whatever label you like the best, though. You can also use them interchangeably.
I got most of this
information from LGBTA Wiki, so credit to whoever made the "Disexual" page on there.