Pattern don't make sense to me

Hi everyone , knitting a pattern which states that I have to add a bead it goes like this ; Slip next stitch purlwise,AB to the next stitch on the left needle ,slip first back onto left needle , S2KP

The S2KP is a centered double decrease.

The reason that you slip a stitch purlwise and then add the bead to the second stitch is so that the bead ends up as the center stitch. Give it a try on a small swatch to make sure it all works for you.

Which pattern are you using?

I am knitting Barbara Rose Shawl by Lynn Wilson Designs Thank you.

Very nice!