Loop stitch with single crochet is a one of the basic crochet stitches.
loop stitch (knot)
At all crochet schemes loop stitch with single crochet symbol would appear as:
At the scheme below you can see a stitches of loop stitch with single crochet.
Loop stitch with single crochet instructions
Wrap the yarn over the index finger of your yarn hand. Insert hook in the last stitch of the previous row under top two loops.
Grab the strand of yarn from behind your index finger, and draw the yarn through the stitch.
The yarn on your finger becomes the loop.
With the yarn loop still on your finger, catch the yarn and draw it through the loops on your hook.
Take the loop off your finger.
You should now see a row of loops on the wrong side of your fabric.
Save this step by step tutorial as a reminder