Hi This line in the pattern means that you are going to knit 18 stitches, you are then going to make 1, Knit 1, 6 times . It looks like in this pattern they are using () to note where your repeats will be. After you are done with your M1, K1 repeats you then Knit another 18 stitches. if my adding is correct when you are done with this section of the line you should have 48 stitches. It looks like the pattern then wants you to cast on 24 stitches this then gives you 72 stitches on the needle.
So if it where written out it would look like this:
Knit 18 stitches, make1 knit 1, make 1 knit 1,make 1 knit 1, make 1 knit 1, make 1 knit 1, make 1 knit 1, knit 18 stitches