A 22nd century Starfleet starship, and second ship of the NX class, the NX-02 was still under construction (and unnamed) at the time of the Xindi attack on Earth in 2153. It was completed and launched in 2154.
The launch date of 2154 is based on comments in ENT: "The Expanse". of the NX-02 being 13 months from completion, and the episode's date of April 24th, 2153.