Understanding a part of a knitting pattern

Part of the knitting pattern I’m having trouble with is as follows: “Work even in St st until piece measures 9” from beginning, end with a WS and decrease 36 sts evenly across last row–62 sts." Question: I do know how to do the decreases across the row but I’m not understanding part of this pattern "…end with a WS and decrease 36 sts evenly across last row – 62 sts. " I would appreciate if anyone can explain I am making this pattern for my granddaughter. Thanks a million!

When you get to the required length, decrease across the last wrong side row (purl side, since you’re doing normal stocking stitch but otherwise, look at what the wrong side is for your pattern). You may need to use a knitting decrease calculator to see how to decrease evenly across the last row. I provided a link to one that I use, but there are others:
https://www.worldknits.com/knitting-calculators