Learn Italian: Il venerdì prendo l'aperitivo con gli amici. - On Fridays I have an aperitif with my friends.

In Italian, putting a definite article like il before a day of the week changes the meaning to a repeated action. So il venerdì means every Friday or on Fridays. If you just said venerdì without the article, it would mean this Friday.

The verb prendo literally means I take. Why is it translated here as I have?

Italians use the verb prendere (to take) for ordering or consuming food and drinks. Saying prendo l'aperitivo is the most natural way to say I am having an aperitif.

Why is the article gli used in gli amici instead of the normal plural article i?

For plural masculine words, the article is usually i. However, because amici starts with a vowel, the article changes to gli to make it flow better when spoken.

The English translation says with my friends, but there is no word for my in the Italian sentence. Why is that?

Italian often drops possessive words like miei (my) when talking about friends, family, or body parts if it is already obvious from the context. Saying con gli amici naturally implies they are your own friends.