Some languages make a distinction based on gender when classifying nouns.
For example in English there are masculine, feminine and neutral gender pronouns – he (MASC), she (FEM) and it (NEUTRAL).
Other languages such as Spanish use gender for all nouns – for example in Spanish a woman is feminine, but so is a hen and a table.
This is grammatical gender, and has nothing to do with with natural sex distinctions.
Indigenous languages vary in their use of gender, so you need to learn the rules specific to the language you are learning.
In Kunwinjku, masculine and feminine are used for people and other nouns, and there are other noun classes for other groups of nouns.