What does an 8AN ORB to 8AN male adapter do?

It joins a port with an 8AN O-ring boss thread to an 8AN male flare fitting or hose end. That lets you run an AN line from a pump, cooler, regulator or tank port.

Does it come with an O-ring?

The description does not mention one. ORB ports seal on an O-ring, so plan to supply the correct size if it is not included.

What material and pressure rating does it have?

Neither is stated. Ask before using it on high-pressure fuel or oil systems, where an unknown rating is a real risk.

Will it fit my 8AN hose end?

The male end is 8AN, which is the standard 3/4-16 UNF flare thread, so it should mate with common 8AN hose ends. Confirm the ORB end matches your port.

Is it worth choosing over Earl's or Fragola?

Those brands publish material and pressure specs and have a long record in racing plumbing. This one is a plain adapter with little information, so it suits low-stress use or a spare.