Learn French: Je vais débrancher l'ordinateur avant de quitter l'entreprise. - I am going to unplug the computer before leaving the company.

In English, we use the "-ing" form after prepositions (before leaving). But in French, prepositions like de are always followed by the infinitive (the dictionary form of the verb). So, "before leaving" translates to avant de quitter. We use avant de + infinitive here because the person leaving is the same person unplugging the computer.

Why use quitter here instead of partir for "leaving"?

You use quitter when you state exactly what or who you are leaving behind; it requires a direct object. Since you are leaving the company (l'entreprise), quitter is the right choice. If you were just saying "before leaving" without mentioning the company, you would use partir.

Does the word débrancher relate to a tree "branch"?

It does! The French verb brancher means "to plug in" or "to connect" (think of connecting a branch to a main system). By adding the prefix dé-, which reverses the action, you get débrancher—literally "to un-branch" or "to unplug."

Could I use la compagnie instead of l'entreprise for "the company"?