I cannot figure this out for the life of me...

And I've searched like hell on Google - Either my Google-Fu is terrible or no one else has asked this question - and if so, I feel like an idiot.

In the picture below, what do the two little tire icons mean? They're circled so there is no confusion at all.

Thanks!!

 

Those are Locking Front Rims

 

They're differentials. Basically when those buttons are pressed, it stops the left wheel from spinning at a different pace than the other wheel, or vice versa.
The reason we use differentials is to help with cornering. When you go around a corner, the inner wheel travels a shorter distance compared to the outer wheel.
How this works is by using an alternate "unused" gear. Despite differentials making everyday driving way easier, it's a paint in the butt to try and rock crawl with unlocked differentials. It's so hard because if one wheel gets lifted of the surface, you're stuck!

 

Ok, once and for all. They're locking hubs, https://en.wikipedia.org/wiki/Locking_hubs, they disengage the front wheels from the axles/diffs to reduce wear and increase fuel economy.