What is the meaning Selvage?
1a : the edge on either side of a woven or flat-knitted fabric so finished as to prevent raveling specifically : a narrow border often of different or heavier threads than the fabric and sometimes in a different weave. b : an edge (as of fabric or paper) meant to be cut off and discarded.
What does Mark SELV STS mean?
The sleeve is marked at the edge stitches (called the selvedge sts). Those markers stay in place as you work the last 2cm. That last 2cm at the top of the sleeve will slot into the body of the sweater at the notch in the front and back (red arrow).