Learn Farsi: داوطلبان خیریه هر روز غذا پخش می‌کنند. - The charity's volunteers distribute food every day.

The singular word is داوطلب (dâvtalab, volunteer). Because volunteers are people, Farsi uses the animate plural suffix ـان (-ân) here instead of the standard ـها (-hâ). While داوطلب‌ها is also perfectly fine in spoken Farsi, داوطلبان is very common in reading and is slightly more formal.

Where is the word for "charity's" or "of the charity" in داوطلبان خیریه?

There is no separate word for "of". The two words are linked by the Ezafe particle, which is a short "-e" sound added to the end of the first word (dâvtalabân-e xeyriye). This invisible connector acts just like "of" in English to show that the volunteers belong to the charity.

How does the verb پخش می‌کنند (distribute) work here?

This is a compound verb: پخش کردن (paxš kardan). پخش means "distribution" or "spread", and کردن is the helper verb "to do". To say "they distribute", we keep پخش exactly as it is and conjugate the helper verb into the present tense for "they", which gives us می‌کنند (mi-kon-and).

How would we change this sentence to say "Let's distribute food" using the new hortative structure?

To suggest doing this together, you would use بیا (biyâ) or the plural/formal بیایید (biyâyid) plus the present subjunctive form of the verb for "we". The sentence would become: بیایید هر روز غذا پخش کنیم (biyâyid har ruz ğazâ paxš konim). Notice that the indicative helper verb changes to the "we" subjunctive form (konim).