What are DLR lights on a S10 pickup?

DLR on a Chevy S10 (and most modern vehicles) stands for Daytime Running Lights. These are lights that automatically turn on when the vehicle's ignition is switched on, regardless of whether the headlights are also on. They improve daytime visibility of the vehicle to other drivers. On an S10, these could be the headlights themselves dimmed, or separate dedicated daytime running lights (often integrated into the headlights or a separate lamp assembly).