Speaking is an essential skill in the English language. To improve your high school English speaking ability, you should practice regularly. Start by participating in class discussions and presentations. Don't be afraid to make mistakes; they are part of the learning process.
Outside of class, find opportunities to speak English with native speakers or in English-speaking environments like language exchanges or English clubs. Watching English movies and TV shows can also help you pick up new vocabulary and listening skills that will improve your spoken English.