What's in a name?
Latin names have a pattern. Most men's names end in -us. Most women's names end in -a.
Sometimes, they had other endings.
All nouns in Latin have gender (masculine, feminine, or neuter). Most nouns in English are neuter, but most nouns in Latin are masculine or feminine. This does not effect the way that they are used; it is just a way to organize them and help us use them.