What are these symbols on the runway?
The first one is the holding position marking. It denotes the entrance from the taxiway into the runway. The dashed lines are in the side of the runway.



The second one is the non movement area boundary mainly for vehicles, which divides the movement and non-movement areas of boundary- the movement area is on the dashed line, for moving into which you'll need ATC clearance.



Images from FAA Guide to Ground Vehicle Operations