New abbreviations

Continue basic pattern straight up: selvedge, 8x patt rep k1, selvedge. For armholes after 34 cm Bo 1x 5sts, eor dec another 5x2 sts.
Do not understand the pattern
Please help

you do have a basic pattern.

knit it with selvedge stitches (either slip first stitch purlwise, knit on subsequent rows or something different, your pattern should tell you)
After you knit (after what you have knit is) 34 cm long, bind off 5 stitches, then bind of 10 stitches equally worked at the end or row (eor should be end of row, right?)

I’m not sure about this though.

You’re going to continue knitting the pattern with no increases or decreases for 34cm. The pattern is set up as 1 edge (or selvedge) stitch, 8 repeats of the pattern stitch, k1, 1 edge stitch. For each armhole, bind off 5 sts and then bind of 2 stitches every other row 5 times. If this is the back of a sweater, do this armhole shaping on each side. For one edge, the bind offs will be on right side rows and at the other edge, the bind offs will be on wrong side rows. If this is a cardigan, you’ll only do the bind off on one edge on each front.