Question about my 'Earning Statement' I got in the mail? So confused

So I quit my job and two weeks later I got my vacation pay (860.06) directly in my bank account, and a week later I got the statement for it saying I had 94.51 hours. My rate of pay is 13.52 so it equalled out to 1277.78 which makes sense, but I only got 860.06 cause I got taxed, which is kind of stupid cause they're vacation hours, should you still get taxed on them?

So further down the page it says in bold "retro adjustments; retro pay" which was the same number as above "1277.78". I didn't know what it meant so I looked online and I guess retro pay is back pay? But isn't my vacation pay backpay? I'm assuming they don't owe me any extra money of the exact same amount but why would they put that on my stub otherwise? I also find it annoying that they said they "back paid" me the 1277 dollars when they only gave me 860.

I really don't know a lot and I'm hoping someone with more experience then I can give me some advice or explain this to me

Thanks for the help!
-a confused 21 year old trying to make it in this world