Yo estudio español.
English: I study Spanish.
Subject pronouns in Spanish are words that replace the subject of a sentence, like 'I', 'you', 'he', 'she', etc. They tell us who does the action.
Use subject pronouns in Spanish to show who is doing the action, especially when you want to be clear or emphasize the subject. Often, Spanish sentences do not need the subject pronoun because the verb form already shows who the subject is.
Yo estudio español.
English: I study Spanish.
Tú eres mi amigo.
English: You are my friend.
Nosotros vamos al cine.
English: We go to the cinema.
Ellos viven en Madrid.
English: They live in Madrid.
Ella canta muy bien.
English: She sings very well.