Supervision is related to how much intervention a tradesperson is taking in terms of assisting you to do your work. When you start an apprenticeship, the supervising tradesperson will watch over you performing your work closely. The supervising tradesperson will make sure that you are undertaking your work correctly and ensure that you are safe from any hazards. At this point, you are working under direct supervision.
When you grow in confidence and in experience, the supervising tradesperson will intervene in your work activities on an occasional basis. In other words, the supervising tradesperson will allow you more scope to work without intervention, and will check from time to time on how you are going. At this point you are working under general supervision.
After further development, you will have acquired experiences, confidence and you will have gained a higher level of technical ability. At this point of your apprenticeship, your supervising tradesperson will no longer have to intervene at all in your work. That is, you will be working without any assistance, and your supervising tradesperson will only be checking the work at the end to ensure the work has been performed correctly and that it is compliant and electrically safe. At this point you are working under broad supervision.