Per wikipedia:
Each team of singers is mentored and developed by its respective coach. In the second stage, called the battle phase, coaches have two of their team members battle against each other directly by singing the same song together, with the coach choosing which team member to advance from each of individual "battles" into the first live round. Within that first live round, the surviving acts from each team again compete head-to-head, with public votes determining one of two acts from each team that will advance to the final eight, while the coach chooses which of the remaining three acts comprises the other performer remaining on the team.
In the final phase, the remaining contestants (Final 8) compete against each other in live broadcasts. The television audience and the coaches have equal say 50/50 in deciding who moves on to the final 4 phase. With one team member remaining for each coach, the (final 4) contestants compete against each other in the finale with the outcome which is decided solely by public vote.