The USS Enterprise (NCC-1701-A) was a Constitution-class vessel operated by Starfleet in the 23rd century. In the alternate reality, this was the second Federation starship seen to bear the name Enterprise.
- See: Enterprise history
Construction of this ship at Starbase Yorktown was underway in 2263. It was completed following the destruction of the USS Enterprise (NCC-1701) during the Battle of Altamid, when it was named in honor of its predecessor and given to Captain Kirk and his crew after Kirk and his senior officers defeated Krall during the attack on Yorktown. It launched out into the unknown with a massive warp bubble. (Star Trek Beyond)
The USS Enterprise-A was designed by Sean Hargreaves, who described it as "evolutionary rather than revolutionary" in its relationship to its predecessor (which had been designed by Ryan Church). Hargreaves also stated that the Enterprise-A was designed with the vulnerabilities of the previous Enterprise being reinforced. He partly based the new ship on a model of that earlier vessel.
The only other ship he used as an influence was the original USS Enterprise (designed by Matt Jefferies), which he had always extremely liked, so he included several visual nods to it, such as changing the rim of the saucer from a near-vertical angle to a near-forty-five degree angle. Hargreaves also altered the silhouette of the craft. Whereas the neck had always leaned forward and the nacelles had always leaned back, he wanted to change the leading edge of those aspects so they were vertically straighter. 
According to Hargreaves: "The brief was to beef up the neck and arms, but I took it upon myself to go further... I worked many long hours at work and after work and weekends on this, knowing the weight of the responsibility, which I didn't take lightly." 
Like the prime reality refit Constitution-class Enterprises, the USS Enterprise-A also has its name inscribed on the ventral side of the primary hull. The ship's registry number is listed above the name in a manner highly similar to the prime reality's Galaxy-class USS Challenger (NCC-71099). The Enterprise also includes six large windows in the bottom of its secondary hull, similar to the prime reality refit.
According to the Star Trek: The Official Starships Collection special issue for the Star Trek Beyond version of the Enterprise, the Enterprise-A is a modified version of the Constitution-class as opposed to a new class.