In order to make a passive sentence, we need a direct object in the sentence.

For the passive voice, a form of the verb "to be" is needed in the tense of the active voice, and then the other verbs changes to past participle.

Present:

My friend usually brings cookies to the office.

Cookies are usually brought to the office by my friend.

The first sentences has a direct object, which is "cookies", which changes to the subject in the passive voice sentence. The sentence is in present simple, so the present simple for the noun "cookies" is "are". The past participle of the verb "bring" is brought.