Learn Farsi: غیبت کردن یه عادت بده.

In everyday spoken Farsi, particularly in the colloquial Tehrani accent, the word یک (yek) drops its final consonant and reduces to یه (ye). It functions exactly the same way but sounds much more natural in casual conversation.

The translation says "is a bad habit", but there is no است (ast) in the sentence. Where is the verb?

In colloquial Persian, the verb است (is) shrinks down to just an "-e" sound and attaches to the end of the previous word. Here, it attaches to the adjective بد (bad). Instead of writing the formal بد است (bad ast), it becomes بده (bad-e).

How do the ezafe and the shortened "is" work together in عادت بده?

There are actually two "-e" sounds happening in a row here, which can be tricky! First, there is an invisible ezafe linking "habit" and "bad" together: عادتِ بد (aadat-e bad). Then, the shortened verb "is" attaches to the end as a written ه: بده (bad-e). When you say it out loud, the whole phrase flows as "aadat-e bad-e".

Why is the full infinitive غیبت کردن used as the first word here?

In Farsi, the infinitive form of a verb (which always ends in -ن) is also used as a noun, similar to English words ending in "-ing" (gerunds). While غیبت کردن is the dictionary form meaning "to gossip", here it acts as the subject of the sentence, translating smoothly to "gossiping".