Is that the only white momentary switch on the lower panel of the dash? If so, then that button is used in the process of jump starting your Ford engine should that battery be drained. As long as you hold the button a relay kicks in and allows coach batteries to charge up the Ford battery. Notice I didn't call it a jump start button, as the size of the wire is not large enough for a quick jump start... It takes a minute or two for the Ford battery to charge up enough to start the engine.
If this is an additional momentary button, I don't know what it would be. Trading the wires would be required.
The red button may require some tracing of the wires. If I were to guess, it is likely a master On/Off switch for the entry step. In the off position the step won't move. This is useful for many situations... Keep them in. Keep them out. Reduce wear and tear from extra cycles. Safer to work on them knowing they're not going to move ant cut off your fingers during a repair or lubrication, etc etc. I added one for this very reason.
Another guess would be a secondary power for the Garmin/stereo... But usually that is not an On/Off switch. Instead it is a On/On switch with one position providing power from the Ford battery and the other position providing power from the coach battery. Look on the back side of the red switch and see how many wires are attached. On/Off would have only 2 wires,,, not 3. If 3 then the middle one will go to the device being powered and the other 2 go to the power sources. There could be a short looped wire in the situation from one post to another for the light... Don't include that in the count. Just count the wires that connect to the switch and go into the dash.
Larry