Every living thing on the face of the Earth was wiped out--people and animals and creatures that move along the ground and the birds were wiped from the Earth. Only Noah was left...and those with him in the Ark. 
The Akkaba Ark was the Apocalypse Twins' spaceship. Their goal was to use it to transport all mutants to Planet X, while Earth gets destroyed by the Celestials and all of its futures erased, including Kang's timeline.[1]
History
The Akkaba Ark was a massive starship that served as the base of operations of the Apocalypse Twins.[2] The ship itself was hidden in the "Akkaba Nebula", a galaxy that had been miniaturized to the size of a Terran sports ball via the use of Pym Particles.[3] It was used to transport all of Earth's mutants during the "Rapture" to their new home, Planet X, after the Earth was destroyed by Exitar.[4]
This was part of the Apocalypse Twins' plan to demolish the kingdom of their cruel adoptive father, Kang the Conqueror, as every single possible future of Earth was erased.[5][6][7] Kang managed to escape into the timestream and assembled the Chronos Corps from other erased timelines.[6] Together, they sent the minds of the Avengers Unity Division back in time to prevent the Twins' plan from succeeding.[8] In the new history, the Ark was destroyed by Sunfire and the Twins were killed.[9]