The battery is totally discharged. Start by charging it at a slow rate for a few hours, then check it again. If it still reads that low, it has a shorted cell and must be replaced.
A good, fully charged battery will read 12.6 volts. If it's good but fully discharged, it will be closer to 12.2 volts. If you find it's considerably higher than 12.6 volts after charging, that's due to "surface charge" and is not accurate. Turn on a load, such as the head lights, for five or ten seconds, then recheck the voltage. Expect it to be near 12.6 volts now.
If this solves the problem for now, let me know, then we'll want to test the charging system to see if it will keep the battery charged. With a dead charging system, a good battery can only run the engine and electrical system for roughly 15 to 60 minutes.
Here's links to some related articles you might find informative:
Let me know what you find up to this point.
Tuesday, January 24th, 2023 AT 2:29 PM