Self-isolation or quarantining, essentially, is to stay at home. You remain at home; you do not go out. Someone else supports you with groceries and all the rest. You remain at home, unless there is some need to seek medical attention or something similar. You remain in your home, separated as much as possible from others who may be in the home. You adopt rigorous cleaning and disinfection-type protocols. You self-monitor closely, and if you develop symptoms, you identify to public health immediately.
For some individuals who have been designated as essential workers, there are exemptions to the quarantine that permit them to leave the home to go to work and to return to the home, but they are expected to maintain the quarantine otherwise.