a Exo is a human consciosness uploaded in to a artifcal body. The number after their name is how many times their mind was wiped and rebooted. Cayde was known for his humor and loyalty.
Cayde was fighting Prince Uldren Sov and the Scorned Barons during a prison riot in the prison of elders.
Cayde-6 is the one on the ground, and Uldren Sov the Awoken prince is the other one