Simplify the following text for a Grade 7 native English-speaking person.
Original: The Victoria line is a deep-level London Underground line running from the south ( Zone 2 ) to the north-east ( Zone 3 ) of London .
Simplified: The Victoria line is part of the London Underground network . It is a deep-level underground metro line that runs from Brixton in the south of London to the Walthamstow Central in the north-east .