This is a transit sign. Transits sign that are like this; white bottom and black letters indicate that a higway is near, in this case is the state highway 158 that runs from near Goldsmith, Texas eastward to Ballinger, Texas. As the sign shows under the numbers of the higway is the state from where it is, this is important also because it tells that is not a interstate highway and only runs inside the State of Texas.
Finally there is an arrow that shows that if you still going forward you will arrive to the highway indeed. You probably are driving through the Texas State Highway 302 because in an intersection of this highway is where the 158 born.
The black and white signs with a number at the top and the word “Texas” on the bottom are called “Texas Route Marker” signs. The word “Texas” under the road/highway (indicated by the number) tells us that the road/highway is only in Texas; thus, it is not an interstate highway. The arrow indicates where the road is in relation to where you are. Thus, the sign you presented here tells us that that Texas highway 158 is forward of the current position, and that if you keep going forward, you will arrive at Texas highway 158.
