Basically, a Feed is the database where the information is stored, so you need to decide what you want to store and look at later.
MSG is the serial number of the message - not likely that you’ll need this, but useful if you have data transmission problems.
Vrms is the mains voltage
P1-P6 are the average powers over the reporting period, the last 10 s approx, in watts.
E1-E6 are the accumulated energies from the initial switch-on, in watt.hours.
T1-T3 are the temperatures (if you have added the sensors)
pulse is the accumulated pulse count (if you have connected it)
missed and missedprc relate to data packets that failed in transmission
rssi is the received signal strength from the emonTx4.
I see you have set up P1 already - the numbers you’re seeing for kWh there should tally with the value of E1 (probably with a static difference as they will have started at different times).
I think you’ll need to play with it for a while to get the hang of it (there’s always the Docs) and then reckon to start again using the knowledge you’ve gained.