Cunfusing instruction

How do you knit into front and back of a next stitch?
And what does this mean “knit into front and back of next stitch, k1-30 sts”?

Each stitch has two legs, one hangs over the front of the needle and that’s the one you usually knit into when making a stitch, the other is hangs over the back. Knit into the front leg, leave the stitch on the needle, then knit into the back. There’s also a video on the Increases page under kfb.

so does the k1-30 sts mean knit one to 30 stitches?

No, at the end of a row the ‘- xx stitches’ means that’s how many are there when you’ve done the increases. So you’ll have 30 sts when you’re finished with this row.