The sign you are referring to is known as the "Transition arrow - no oncoming traffic 1-lane to the left and 1-lane straight ahead."

This sign indicates that vehicles can either continue forward in the lane or shift to the left. It specifically informs drivers that there are no oncoming vehicles blocking the left lane. Essentially, if you are driving and you see this sign, you may choose to go straight or change to the left lane if it is safe to do so.

Always ensure to check your mirrors and signal your intentions before changing lanes to maintain safety on the road. If you have any more questions about traffic rules or need clarification, feel free to ask!