Explain this to me like I’m 5

Please explain this: “Our policy allows for payout of a pro-rated amount of vacation hours, as if the time had been accrued (earned) on a per pay period basis. Accrued hours that you used are not paid out. Please let me know if you have any questions.”

Okay seriously what does this mean? I’m so confused and HR is NO help. I recently resigned from my position and this is what I was told.