Spanish has two ways to say "you" in singular: tú (informal) and usted (formal). Use tú with friends, family, classmates, and children. Use usted with people you don't know well, older people, authority figures, doctors, and in professional settings. In Latin America, usted is also commonly used between parents and children as a sign of respect. When in doubt, start with usted — it's better to be too polite than too casual.

In Spanish, subject pronouns are often omitted because the verb ending already tells you who is doing the action. Hablo español means "I speak Spanish" — you don't need to say Yo hablo español. However, you should include the pronoun when: (1) emphasizing or contrasting — YO voy, no tú (I'm going, not you); (2) the context is unclear; (3) using usted/ustedes to be polite.