Common Japanese knitting symbols in patterns
Common decrease/increase notation
A x-y-z sequence means: knit another x rows - decrease/increase y stitches - do this z times.
So the above decrease should be done like this:
2. Knit 2 rows, bind off 2 stitches, do this twice
3. Knit 2 rows, bind off 1 stitch, do this 5 times
4. Knit 4 rows, bind off 1 stitch, do this 3 times
5. Knit 6 rows, bind off 1 stitch, do this 4 times
Let's do the math now: 7 + 2x2 + 1x5 + 1x3 + 1x4 = 23 stitches.
Other very useful resources on Japanese Knitting