Grammatical gender has nothing to do with social gender, it’s just a simple way to communicate that there are classes of words which belong together. Some languages have gender pairs (e.g. Masculine and Feminine words), and some languages have more genders (e.g. Latin’s Masculine, Feminine and Neutral). Some others yet have a mix of genders still in use and active, still in use exclusively for historical reasons, and completely unused (e.g. Portuguese has active use of Masculine/Feminine, but Neutral gender is only present as an inherited holdover.).

That’s why @leftzero did answer the question - insofar as to state the question was incomplete to begin with. What does it mean to “deal with non-binaries” when a language isn’t binary in its gender?

As a curiosity, the Portuguese word for “a person” is always feminine (“uma pessoa”), but for “a citizen” can be either masculine or feminine (“uma cidadã”/“um cidadão”). This is very common, and greatly illustrates how grammatical gender is largely disconnected from social gender. For an example on neutral gender, “president” takes a gendered article but is never masculine nor feminine (“um/uma presidente”).