From Tolkien Gateway
The Second Hall was one of many Halls of Moria. Between the Second and the First Hall - counting from the entrance of the city - lay the ill-fated Bridge of Khazad-dûm in the First Deep.
In T.A. 2994 Orcs joined battle with the Dwarves of Balin's Colony in the hall. During the ensuing brawl Lóni, Náli and Frár were killed while the rest escaped to the Seventh Level, allowing the Orcs to reclaim the Hall.
It was the largest encountered by the Fellowship of the Ring while they traversed Moria. Its pillars were notable for being smooth and black, carved like trees, with the boughs holding up the ceiling. On their way to the First Hall they met Durin's Bane, and where Gandalf fell into the chasm.