"It is alive!"
However, it goes deeper than that. "Ka Mate" actually refers to the Maori god Tāwhiri-mātea, the god of the winds and weather, and the war cry expresses a belief that the god's spirit is alive within the warrior. It conveys a sense of strength, vitality, and invincibility.
The full war cry is actually "Ka Mate, Ka Mate! Ka ora! Ka ora!" which translates to:
"It is alive! It is alive! It is well! It is well!"
This emphasizes the resilience and power of the Maori people.