The Mezzanine

You're in the rightmost lane and you merge into the cars going from your left to your right, as you would if you were changing lanes.

I would guess that it's functionally identical to a "turn left any time with care" sign, except that it's the default here and we instead have "no right turn on red" signs at intersections where it's not allowed.

(You can never turn left on red here. I can't speak for everyone's driving lessons but my teacher drilled it in really hard: NEVER turn left on red.)