German knitting pattern

I have found a pattern for something that I really want to knit - the problem is - it is German. I found this pattern on the Lana Grossa yarn website and it is translated into English however it doesn’t use a technique I understand.
Could someone explain what this means?
At a height of 34 cm from border co 1 x 5 sts, 12 x 3 sts and 2 x 2 sts each in every 2nd row at right edge for shoulder slant.

The same technique is used later as well. Help!

row 1 you cast on 5 sts
rows 3,5,7,9,11,13,15,17,19,21,23,25 cast on 3 stitches
rows 27 and 29 cast on 2 stitches

the rows in between knit even (i.e dont do anything different)