Is the 40 lb limit enough for groceries?

For a light run, yes. A full week's groceries for a family will likely exceed 40 lb, so plan on smaller trips or a trailer rated higher.

Can it carry a child?

It is marketed as a child trailer and stroller, but the listing gives no child weight limit or harness details. Confirm the seat and harness with the seller before towing a child.

How does it compare with a Burley or Thule trailer?

Those cost several times more but carry 100 lb or more, use better hitches and hold resale value. The Ktaxon is a budget option for light, occasional loads.

It uses a hitch that mounts at the rear axle. Most bikes work, but thru-axles and some disc-brake setups need an adapter, so check your axle type first.

Expect the trailer frame, two 16-inch wheels, the removable cover, the hitch and assembly hardware. A stroller kit is not confirmed, so ask the seller if you need one.

Budget trailers like this see the deepest discounts in late fall and winter, outside bike season. Compare across stores rather than buying at the first listing you see.