These are white H shaped advisory markings that are painted in front of a driveway to draw attention to a dropped kerb and encourage people not to park across it.
The marking is only painted across the extent of the dropped kerb, from one taper to the other. If you want the marking to go across a neighbour’s property you need to have written permission from the owner or occupier.
This also applies to shared access – all properties will need to agree in writing.