"She is introducing her child."

Translation: Elle présente son enfant.

[Bert791687]

why is "elle introduit son enfant" false ?

[Virginia71473]

Why can't it be sa enfant?

[JoanSmith0]

Why does the verb have to agree with the gender and is that the rule for all French verbs?

[relox84]

Verbs do not agree in gender (well past participles do sometimes, but that's another story).

The -e at the end of présente is not a feminine mark, but the expected ending of a regular -er verb in 3rd person singular. The ending would be the same if the subject were masculine (il):

Je présente | Tu présentes | Il/elle/on présente
Nous présentons | Vous présentez | Ils/elles présentent