The (k1 yo k1 yo k1 yo k1) in next st is a way of increasing. All 7 steps are made into the one stitch on the left needle before that stitch is dropped off the needle. See if this video
helps at least show you the idea of what you're to do. Keep going until you have 7 loops over the needle in the one stitch.
The -30 is just telling you the total number of sts you should have at the end of the row, your 24sts plus the increase of 6sts.