No soldering required, you just plug it onto the header on the Raspberry Pi.

yes/no. it's sized to match the Pi Zero, which by default comes with no headers - so to add this board you'd need to add headers. But many vendors (including OP) offer them pre-soldered, which makes the hardware side "plug the top bit into the bottom bit".

(The zero is positioned as the "barest of bare-bones" to reach its price-point. Many vendors look for value-adds they can offer because there's not much margin on "barest of bare-bones". So "no headers" is one of the ways the manufacturing price was lowered, and "with headers" is one of the value-adds some vendors offer.)

So not to contradict anyone, just to be clear that you're looking for "pre-soldered" or "pre-soldered headers" if that convenience is worth the extra couple of bob to you - to avoid the disappointment of expecting one and receiving the other.