Severance is a procedure that separates memory based on location. After taking the procedure, when leaving the work place you hold no memories of what happened there. Likewise, when you are at work, you hold no memory of your life external to the workplace.
Severance ensures that your work-self retains basic knowledge (general information about the world, what your name is, how to read write shit etc) but not any personal information (family, hobbies etc).