as cleared already.. DRL means daytime running lights. As soon as the headlight switch ON the DRL goes low in brightness.
As an additional general knowledge. DRL on most of the cars with exception of Civic... cut off/ shut's off when you turn on indicator / signal. means on these cars if you tun a right or left indicator ON, the DRL on that side goes off, to make a turn signal more prominent and visible. as DRL are high intensity and there are chances that pedestrian or any other car driver might not see it properly if DRL remains ON.
Civic X DRL remain constant ON.. There is no federal regulations here in US about it but studies have shown that cutting a DRL off is much better and makes a car signal/ indicator more visible. Chances are Civic follow Germans on this in future and also introduce this feature.