The meaning of the arrow is totally dependent on which function mark it's near. An arrow near the [A] mark indicates the side of the car for which the parking lamp is approved. This kind of arrow always points outboard (away from the centerline of the car) when the device is properly installed, so if the arrow points to the left as you view it, it's for the right front or left rear of the car; this applies to all turn signals, parking lights, brake lights, reflectors, basically any function that is not a headlamp. An arrow on a side-mounted device (turn signal repeater, side marker light) points towards the front of the car when the device is properly installed. The possibilities are:
⇐ (device is for right front, left rear, or left side mounting)
⇒ (device is for left front, right rear, or right side mounting)
No arrow means the device is suitable for use on either side of wherever it's destined to go (front, side, rear).
An arrow near a low beam headlamp function marking such as [CR], [HCR], [HC/R], [HC], [DC] or [DCR] indicates the side of the road for which the headlamp is intended. Possibilities are:
No arrow (the headlamp is for use on the right side of the road)
⇒ (the headlamp is for use on the left side of the road)
⇔ (the headlamp can be adjusted for use on the left or right side of the road)
There's more detail on
Stern's lens markings page.
