Online Mode in Red Dead Redemption 2 (RDR2) is a feature which allows players to play a vast selection of multiplayer modes.
Online Mode in RDR2
The BETA for Online Mode is confirmed to return to Red Dead Redemption 2, on a later date to the game's initial October 26th release date. It will feature a variety of game modes including a free roam mode that allow you explore the full map of the single player experience either with a gang or on your own, and let's you evolve and grow your character to a good extent of what is available in the single player mode.
There is no word on when the full Online Mode will drop, but the beta should show us what they are trying to do and expand upon