Confusing pattern... please help!

I’m working on a cardigan that has been a little tough to figure out. I’ve reached the point where the armholes begin, and the pattern reads:

The armhole line: 36 stitches leaf pattern, 10 stitches bind off, 71 stitches leaf pattern, 10 stitches bind off, 36 stitches leaf pattern. Then bind off three stitches together once, one stitch three times on each side. (<- this part confuses me… how do I bind off 3 stitches together, and what does the rest of the sentence mean?)

Following is this:

Then on the armhole side work even; to round off the neckline, bind off one stitch 13 times in every second row (the wrong side). Then knit even the leaf pattern for the next 10 cm. You can round off the back. To do that, in the middle bind off 15 stitches once, then 3 stitches together once and knit 3 times 2 stitches together. Bind off all stitches at 50 cm from the beginning of the needlework.

**** I just want to make sure I have this figured out right… does the “armhole side” mean the stitches leading up to the bound off armhole? if this is the case, am I supposed to knit up to that point and keep turning the work (for both sides, then the back)? Thus far, the piece is supposed to be knit as a whole so where do the sides and back meet back up? I apologize for all of the questions, but I am very new to knitting sweaters

Sounds like this is knit seamlessly to the underarm which will be the 10 sts you BO. The sections will be knit back and forth separately. At the armhole edge you continue to BO 3 sts at the beg of a row, then dec a st on 3 rows; this is usually done on every other row, rather than every row, though you have to do it at both edges of the back. At the neck edge (this will be the front sections, not the back section), dec 1 st every other row 13 times. To shape the neck on the back section, BO 15 sts in the middle for the nec, and BO 3 sts on both sides of that, then dec at each side of the neck 3 times.

It appears to be translated and can be confusing because they use BO, dec and knit together (which is the dec) interchangeably. Instead of the BO 3 times, you could k3tog instead though.