More information about direction signs can be found in the AIM:
AIM 2-3-10: Direction SignsDirection signs have a yellow background with a black inscription and are normally located on the left side of a taxiway.
Below is a sign that is accompanied by a location sign indicating the current taxiway.
Notice that all of the taxiways to the left are left of the location sign and all of the taxiways to the right are to the right of the location sign.
When indicating an exit from a runway, the direction sign will be located on the same side of the runway as the exit. The sign will look similar to what is shown below:
When there is only one intersecting taxiway, it can be indicated with a direction sign that has arrows pointing in both directions that the taxiway cross through, as shown below: