This is the map of the Meridian City also known as Khi Tasira. You visit this location during The Journey to Meridian mission. You should check this mission description for more information about this location, its secrets, etc.
The following legend of Meridian City / Khi Tasira interactive game map defines the points of interest / markers displayed on the map. Each marker corresponds to a specific element to facilitate efficient navigation and interaction with the map.
Investigations at Khi Tasira reveal that the Remnant were built by a species or faction known as the Jardaan. This technology was intended to foster life that the Jardaan had created, using the vaults to manage planetary ecology strictly, controlled from a central point known as Meridian.
The Scourge destroyed the connection from Meridian to these vaults and deactivated many of the Jardaan's technological creations. The Jardaan left the cluster soon afterwards for an unknown location, leaving their technology behind as remnants of their civilization in Heleus.