The answer is: The decision affirmed the protection of symbolic speech.
Tinker v. Des Moines revolved around an activism movements that conducted by students led by Mary Beth Tinker. She organized the students to wear black arm bands to school in protest of the vietnam war.
At that time, the school admins shut down the activism since they see that wearing an armband is not a 'speech' and cannot be protected under the first amendment.
They later on brought the case to the court. The court decided that wearing an armband is a form of symbolic speech that is included under the protection of the first amendment.
