This is also referred to as “two person method”. Here one person pumps the brake while the other bleeds the brake line at the same time.
This is commonly known as the “one person method”. It is also considered faster and easier.
Overall, the goal when bleeding brake lines is to squeeze or push out the old fluid without allowing any air back into the system. If air does enter the system it can be a big problem. Visit our previous posts on how to properly bleed your brakes.