Having trouble with K1P1,yo

Hi, I’m knitting a top called the Cordia Tank by Kerri Blumer. I’m having trouble with the ‘Strap Shift set up row.’ The instructions say, K1P1 2 times, yo, PM, K1P1 2 times, etc. Im having trouble with the K1P1, yo. I realise that yo means yarn over but after you’ve purled, does this mean that you take the yarn back to a knitting position which is sort of bringing yarn over or am I missing something. I’m sure it’s really simple but I can’t seem to get it right. TIA

Welcome to KnittingHelp!
Yes, that’s it. Bring the yarn to the back over the needle. Then it’ll be in position for the next knit stitch. Don’t pull too much on the yo because it’ll shorten it and it already seems to be rather short.

It’s shown about 1:30 min into the video.

Thanks for your help. Making sense now:)