Learn Farsi: گناهکارها جریمه را پرداخت می‌کنند.

گناهکار is an adjective meaning "guilty" (or a noun meaning "sinner"). By adding the regular plural suffix ها, we turn the adjective into a plural noun: گناهکارها (the guilty ones / the guilty people). This is a very common way in Farsi to talk about a specific group of people characterized by an adjective.

What are the parts that make up the word گناهکار?

It is built from the noun گناه (sin, guilt, or fault) and the suffix کار (doer or maker). Together, they literally mean "the doer of a sin," which translates to "guilty" or "sinner."

Why is را used after جریمه?

The word را is the specific direct object marker. Because the sentence says they pay the fine (a specific fine, not just any fine), جریمه needs را to show it is the direct target of the verb پرداخت می‌کنند.

Why must the verb پرداخت می‌کنند be in the plural form here?

In Farsi, when a plural subject refers to living things (like humans), the verb must be plural. Since گناهکارها refers to a group of people (the guilty ones), the verb takes the third-person plural ending ـند to match it. This is a good reminder, as inanimate plural subjects in Farsi can often take singular verbs.