it comes form here "Elle apporte du lait. "

i would look in the food section

I found it when i put the word ''apporte'' in the search section of the forum

apporte - Verbs: Present 1. Lesson 3: https://www.duolingo.com/skill/fr/Verbs%3A-Present-1

apporter - Infinitive. Lesson 4: https://www.duolingo.com/skill/fr/Verbs%3A-Infinitive

It also appears in other lessons, but the two above are its main locations. No guarantee that it will show up in your lessons or strengthen sessions.

some woeds just never show up, it just sometimes happens but as long as you know it's meaning i don't think it's a problem