Please help with vest pattern

Hello, I am new to this, so if I do something wrong please forgive me. Anway, I knit the back of the vest and the left front. For the right front piece it says to do like the left front piece, but mirrored. What does that mean??

It means to reverse the shaping. So if there’s a BO at the beginning of a RS row, you do it on the begininning of the WS row. For decs you’d do them on the end of the row.