There are actually three forms which may cause confusion:

• tú (with accent) = you (subject pronoun)
• tu (without accent) = your (possessive adjective)
• te = you (direct or indirect object pronoun)

Some examples may clarify this:

• Tú tienes el libro ("You have the book")
• Este libro es tu libro ("This book is your book")
• Yo te doy el libro ("I give you the book": "te" as indirect object)
• Yo te golpeo con el libro ("I hit you with the book": "te" as direct object)

te can also be a reflexive pronoun; that is, the object of a reflexive verb:

• Te lavas ("You wash yourself")
• Te lavas las manos ("You wash your hands")