In the world of Lumon, a person who has undergone the Severance Procedure has had their consciousness and memories bifurcated into two timelines: that of their Innie, and that of their Outie. Those are colloquial terms but they are used with such consistency among all levels of management that they must be somewhat official terms.
An innie is the person who only exists at work, whose life began on the table in the Waking Chamber and whose day begins and ends in the elevator down to the severed floor where they work. An innie has no knowledge of the year, the world, their own outside lives, or anything other than Theories About Macrodata Refinement.
An outie is the person who elected to undergo the severance procedure, who sleeps and lives in the world, who has no memory or knowledge of their work at Lumon or the suffering that their innie can experience while severed.
An innie who sustains an injury on the job knows how the injury occurred; the outie will only become aware of it when they ascend the elevator at the end of the day. Generally, Lumon devises an everyday sort of explanation for their sudden abrasion or pain, enclosing it in a note left on the employee's windshield.
When, in episode 7, Defiant Jazz, Seth Milchick activates the Overtime Contingency Protocol for Dylan George, he awakens his innie after work hours, away from Lumon in his outie's house. There, Dylan saw his son, a person he had no idea existed in his innie state. This experience changes Dylan forever.
In episode 9, The We We Are, Irving Bailiff, Helena Eagan, and Mark Scout also activate their innies in the outie world with the heroic assistance of Dylan, where they learn as much as they can and communicate as much as they can the problems that they, the innies, are experiencing in that state, locked away from all other awareness.