This is the 1972nd most frequent Portuguese word.
vivo
Alive; live.
Here 'vivo' is used as an adjective meaning 'alive', describing the state of being living.
Eu estou vivo e cheio de energia.
I am alive and full of energy.
In this sentence, 'ao vivo' is used as an adverbial phrase meaning 'live.' It indicates that the broadcast is happening in real time.
Esta transmissão está sendo feita ao vivo.
This broadcast is being made live.
Here 'vivo' is used as an adjective, meaning 'vivid' or 'bright,' describing the sparkle in the eyes.