tikidoll,
I remember when I purchased my first machine. I was stumped by this as well.
Stitch functions refer to what you can do with a stitch. For example the zigzag can be used to 1-finish a raw edge, or if you make the stitch length shorter you've got a satin stitch that can be used for 2-applique 3-monogramming. The straight stitch 1- seaming, very long = 2 basting. These are all stitch
functions. Some machine companies will now state that a particular machine has x number of
actual stitches. I think the whole
stitch function thing can be misleading for newer sewists. A machine is advertised as having
100+ stitch functions yet you can only count 60 stitches

.