What does this mean:
Total Paid (Last month) 19.848 DASH (6 times /
1 missed /
1 hijacked)?
I added the color for dramatic effect

i had same question week ago, but nobody answered me

i also have one Hijacked

So I guess this will remain a mystery. I draw some guilty pleasure out of it, for someone's MN has "hijacked" my payment but the one my MN "hijacked" from someone else was 100% higher.

Missed means your masternodes was in blocktemplate payee but was not payed (either a block not paid, or paid to another pubkey).
Hijacked means your masternode was NOT in blocktemplate payee but was payed (you "stole" the payment from someone else).
You should see below the details of the payments, when red background on the Masternode Expected column then you hijacked a payment.
When red background on the Masternode Paid you missed one.
I hope it is cleared. Will try to add a tooltip for next version.
your sig link has problems.