Yes I’m stupid. What are these controls?

They show the amount the floor vent flaps on the bottom of the HVAC unit are open (which allow air into the footwell areas, but, correspondingly, reduce the amount of air coming out the dash vents). More LEDs lit = floor vents more open. See Instruments & Controls in Section 1 of your OM (but agree that their operation is not well-described). The symbols with the two arrows on each side (at the unlit end of each LED bar) represent all of the air for that side going to the dash vents; whereas, the symbol with the three arrows in the middle (at the lit end of each LED bar) represents (some lesser) air going to the dash vents and some air going out the floor vent for that side. Likewise, the symbols on the switches -- when you press the switch direction with the 4 arrows = less LEDs for that side (and more air out the dash vents), and pressing the switch direction with the 3 arrows = more LEDs for that side (and some air out the dash vents and some air out the floor vent).