General "speak":
* گفتن (goften) - This is the most common and versatile word for "speak". It can be used in many contexts, like "He spoke to me" or "She speaks English."
* حرف زدن (harf zadan) - This literally means "to hit words", and is a more colloquial way of saying "speak". It's often used when talking about casual conversations.
* صحبت کردن (sohbat kardan) - This means "to talk", and is often used in formal settings. It's more appropriate for discussing serious topics.
"Speak a language":
* حرف زدن به (harf zadan be) - This means "to speak in (a language)". For example, "He speaks English" would be "او به انگلیسی حرف میزند" (oo be engilisi harf mizane).
* زبان ... را بلد است (zaban ... ra balad ast) - This means "knows (the language)". For example, "She knows French" would be "او زبان فرانسوی را بلد است" (oo zaban farsi ra balad ast).
"Speak up":
* صدایت را بلند کن (sedayet ra boland kon) - This means "make your voice loud".
* بلندتر حرف بزن (bolandtar harf bezan) - This means "speak louder".
The best word to use will depend on the specific situation. If you're unsure, "گفتن" is a safe choice that will be understood in most cases.