Pronunciation is the way words are spoken. Sometimes you can tell where someone is from by their pronunciation of certain words. Pronunciation is one of the hardest parts of learning a new language.
Reading a language and speaking it are two very different things. If you know French but your pronunciation of French words is wrong, French people won’t understand you. In English, the pronunciation of some words varies, depending on where people are saying them. For example, Americans say “tomato,” and the Brits say “tamahto.” The word pronunciation comes from the difficult-to-pronounce Latin root pronuntiationem, which means “act of speaking” or "a proclamation.”