Is 72 megapixels realistic for this camera?

No. A compact body at this level cannot deliver true 72MP detail; expect heavily processed, phone-like images at best. Judge it by sample photos, not the number.

What does the 16x zoom mean?

The listing calls it a 16x optical zoom, but no lens range is given. On a body this small, expect a modest zoom with softness at the long end rather than a true telephoto.

Does it work well in low light?

Small-sensor compact cameras struggle indoors and at night. Expect noisy, soft images in dim conditions and use it mainly outdoors in daylight.

What comes in the box?

The package lists one digital camera only. No memory card, cable, charger or strap is stated, so plan to supply those separately.

Is it a good first camera for a child?

It is simple and light, which suits beginners. But image quality is limited, so a used phone or a basic name-brand compact may serve better for similar money.