What is (knit 1, slip 1) twice?

I’m trying to knit a baby afgan with a checked design, and my product never looks like the picture. Instructions are to slip as to purl with the yarn on the wrong side of the fabric. Alternating rows have me knitting and purling in various combinations with (knit 1, slip 1) twice in every row. How do I do this step with the right outcome? Thanks.

Knit a stitch, slip a stitch from one needle to the other, then repeat. K1, slip 1, k1, slip 1. When you slip the st, the yarn remains in back, insert the needle into the stitch as though to purl it, then knit the next st.

The biggest mix up for me is not reading the pattern carefully or getting my pattern stitches or stitch count wrong. Sometimes it helps if you practice on a small swatch with maybe 15 or 20 stitches in scrap yarn before you take the plunge and do a big project with that stitch. If I mess it up, I just unravel it and keep practicing the stitch until I get it right. Then I can cast on with the good yarn and knit my big project with confidence.