Beetle CM-32U4, SKU DFR0816, question about how this mounts on the PCB?

Looking at the Beetle CM-32U4, seems like a good fit for a project I'm working on.

Clearly it takes a row of header pins on each side, which can plug into breadboard or a socket.

My question - the CM-32U4 has a second row of holes on each side of its PCB. What's the purpose of these?

Is it like the castellated holes on the sides of an Arduino Nano Every, which is meant to solder direct onto a PCB, without using any pins?

Thanks!