DECaPS2 is a five-band optical and near-infrared survey of the southern Galactic plane with the Dark Energy Camera (DECam) on the 4.0m Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. The survey is designed to reach past the main-sequence turn-off at the distance of the Galactic center through a reddening E(B-V) of 1.5 mag, with a typical single-exposure depth of 23.7, 22.7, 22.2, 21.7, and 20.9 mag in the grizY bands, and with average seeing around 1''. The footprint covers | b | %3C 10 deg , 6 deg > l > - 124 deg (essentially the low latitude Galactic plane south of delta %3C - 24 deg , a total of about 2700 square degrees (6.5% of the sky). DECaPS2 simultaneously solves for the positions and fluxes of all the sources in each image, delivering positions and fluxes of 3.32 billion stars with up to 5 mmag repeatability. Most of these objects are highly reddened and deep in the Galactic disk, probing the structure and properties of the Milky Way and its interstellar medium.