When people or groups are all on the same page, working for the same goals and doing the same thing, they are unified.
Just like the word United in Unified States, unified is a word that means being together. Unified is the opposite of divided. In boxing, there are often a bunch of champions, but every so often, the champions fight to produce a unified champion — one champion everyone agrees on. A similar word is union — a unified group of workers with the same goals, who work together to achieve those goals. People tend to get more done when they are unified.