Learn Farsi: نماینده باید با شرکت‌کننده‌ها صحبت کند. - The representative must talk with the participants.

شرکت‌کننده is an agent noun (a word for a person doing an action). It is built from the compound verb شرکت کردن (to participate). To form it, we take the present stem of کردن, which is کن, and add the suffix ـنده (-ande) to make کننده (doer). So, شرکت‌کننده literally means "participation-doer". Finally, the ها at the end makes it plural.

Is نماینده (representative) also formed with the "-ande" suffix?

Yes! It comes from the verb نمودن (to show, to present). The present stem of this verb is نمای (namāy). When you add the ـنده (-ande) suffix to that stem, you get نماینده (namāyande), which essentially means "one who presents" or "representative".

Why is the verb at the end صحبت کند (sohbat konad) instead of صحبت می‌کند (sohbat mikonad)?

This is because of the word باید (must) earlier in the sentence. In Farsi, words expressing obligation, desire, or ability require the following verb to be in the subjunctive form. For the compound verb صحبت کردن (to talk), the present subjunctive drops the usual می (mi-) prefix, leaving us with just صحبت کند.

Why are the letters disconnected in the middle of a single word like شرکت‌کننده‌ها?

This word is typed using "half-spaces" between its different parts: (participation), (doer), and (plural marker). Farsi writers use half-spaces to keep long compound words and suffixes readable. It prevents the letters from joining together into one giant, confusing block of text.