Y-stitch is a one of the basic crochet stitches.
two double crochet crossed stitch (y-shape)
At all crochet schemes Y-stitch symbol would appear as:
At the scheme below you can see a stitches of Y-stitch.
Skip the first six chains from the hook. Yarn over twice and insert your hook in the seventh chain under the back loop.
Work one treble crochet. Chain one stitch, yarn over and insert your hook in the treble crochet under the lower loops.
Work one double crochet.
Yarn over twice and repeat the preceding steps inserting the hook in the third chain of the previous row.
Repeat the process skipping two chains.
Save this step by step tutorial as a reminder