Right Twist (RT)

The Right Twist stitch creates a mock cable, crossing one stitch over the one to its right.

Working with the next two stitches on your left-hand needle, bring the yarn to the front of your work and knit the second stitch but leave it on the needle. Then knit the first stitch on the left-hand needle as normal. Finally, slide both of the stitches you've been working with off the left-hand needle. Twist complete!

This video from New Stitch a Day (and the corresponding written instructions) is quite clear. The actual instructions start around 2:27.

You can also work it as a C2B, if that's easier for you.