Where are the arm holes?

I am new to knitting and am still trying to understand patterns.

I am making a Debbie Bliss shawl-collared sweater (pg 28 in “Quick Baby Knits”) for a 4 year old.

The directions for the back read “work st st until back measures 19 in from beg ending with a p row” Got it-

Then the directions say “shape shoulders”. Are there no arm holes?

Without seeing the pattern, it’s kind of hard to tell. But here’s a link to Debbie Bliss pattern errata. I don’t see the book you mention, but the pattern may be a reprint. It’s worth a look:
Good luck!

I expect that shaping the shoulders makes the armholes. Are you instructed to do any bind offs at this point?

A drop shoulder won’t have armhole shaping, it’s just straight up. Look later on to see if it says to sew the sleeves X inches down on both sides of the shoulder seam - that’s a drop sleeve.