The Progress MS-06 spacecraft has been placed into orbit by a Soyuz 2 1-A rocket out of Baikonur Cosmodrome. It carries 2450 kg of cargo, including 705 kg of propellant, 50 kg of air, and 420 kg of water. (The ISS has a water reclamation system, but it is not able to provide 100% of the crews’ needs as yet.) Among that cargo is a set of four nanosatellites which will be hand-launched by cosmonaust during a spacewalk. Progress MS-06 will dock with the Zvezda module’s aft compartment, allowing it to transfer propellants into Zvezda’s tanks.
Progress MS-06 was originally slated to dock with Pirs, which it would then carry with it for disposal at the end of its mission, freeing a docking port for the Multipurpose Logistics Module “Nauka”, which has faced numerous delays going back years. Unfortunately, Nauka encountered more delays and is no longer scheduled to launch before 2018. Therefore, Pirs will remain at the ISS when Progress MS-06 departs. Pirs does double duty as both a docking compartment and an airlock for EVAs mounted from the Russian segment; Nauka is equipped with an airlock as well. Even if there is no Russian airlock, there is of course the Quest airlock on the US segment, but it is generally preferred to use the closest airlock to a given worksite.