An American in Provence

One thing that you learn very quickly when starting to learn french is that absolutely everything has a gender. And you had better know it, because the entire way the sentence is constructed depends on it. Whether you use un or une, le or la, du or de la, verb endings, the ending of the adjective, the possessive form mon or ma, etc.
Example: Je mange la pomme. (I eat the apple.)
Je la mange. (I eat it)
In the passé composée form it gets interesting. Since apple is the direct object, the ending of the verb has to accord with it.
Je l'ai mangée.
But if there is no direct object, such as I ate yesterday, it is just
J'ai mangé hier.
It can be difficult to guess what gender the noun is, as there doesn't seem to be any logical assignment of the gender.
lipstick : le rouge à lèvres
tampon: le tampon
(side note: tampon can also be stamps, which leads for some interesting store signs. Kind of like the Supermaxi grocery store in Ecuador.)

The passé composée verbs can be conjugated with être (to be) or avoir (to have). When I took Intro to French back at UVA, I mistakenly thought that it was a direct translation of english, such as
Je suis entrée (I was entering)

But no, it is entered. Note the extra e at the end of entrée when a woman is speaking.
For a man: Je suis entrée.
For we: Nous sommes entrés (for a mixed gender group)
but for a group of women: Nous sommes entrées.

It can be very confusing sometimes. Especially as you cannot hear the difference in the pronounciation, only can guess by the context and who is talking. Same as with the 3rd person singular he/she il/elle, and the 3rd person plural they ils/elles, many times, but not always, the verb endings sound the same.