Not sure what to make of these readings.
Starting at the 27.2 kWh that is 'available' to the user on a new 94ah i3 according to BMW, the 13.08 menu item (Batt. Kapa. Max) is the closest thing the car comes to telling you what the state of health of the battery is. It is an estimate
and can change by a kWh or few from one day to the next, so it should be taken with a grain of salt but it's the best we have.
Since your Batt Kapa Max number is 28.8, that's a good sign your battery is very close to "new" capacity. The math would suggest you have 106% capacity from new, but the precision really isn't adequate for such a number (it could easily be 26.8 tomorrow).
The other two numbers are just battery charge remaining, displayed in % then kWh. The % is the same number you'll see in the car's computer by toggling through options on the turn signal stalk though for some reason the 'hidden menu' doesn't have decimals. You can arrive at another "Maximum capacity" estimate by dividing 24kWh/86% and getting 27.9 kWh for a full charge.
The 27.9 number seems to agree that your capacity is still very high (and possibly over 100% of BMW's stated original 27.2kWh capacity).
For 55k miles, that's pretty impressive that the car hasn't seemed to have lost anything since new!
*Disclaimer -- If you're considering buying this car, don't use this as your only data point on battery health. To my knowledge there is no way to trick the Batt Kapa Max reading but that doesn't mean it's impossible!