You mean other than "The hybrid battery system voltage is low." ?? It likely means that your HV battery is failing or the connections are corroded. It certainly means that you need to have someone who KNOWS what that means to have a look at it.
MONITOR DESCRIPTION The battery ECU monitors a voltage of the battery blocks to detect an open malfunction in internal battery voltage sensor circuits of the battery ECU and the wire harness between each battery block and battery ECU. If a voltage at one of the battery blocks is below a standard level or of all the battery blocks is within a specified range, the battery ECU judges that there is an open in the internal sensor circuit(s) or wire harness. The battery ECU then illuminates the MIL and sets a DTC. Now, in laymans terms, as mentioned above, it's basically saying you likely have a problem with a module voltage, the busbars that connect the battery modules together, the voltage sensing harness or the ecu in the HV battery.
Usually when I get this code the first thing I do is look for corrosion in the hyrbid battery ECU where the voltage sensing harness plugs in. IF you're lucky you clean the pins with sandpaper and clean away all the corrosion. If you're unlucky you have to replace voltage sensing harness ($50 new) and sometimes the ECU itself ($100 used or $800 new)
