What dose this mean ?

Question

Express shipping and hazardous items Note: We're sorry. We cannot ship orders next-day or two-day

Answer 1

It means that you will wait longer for an order if the shipping address is to a military or post office address OR if you have ordered something that may be considered hazardous.  Sometimes "hazardous" is as everyday as perfume, in my experience.  You need to check either your address or what you have ordered.

Answer 2

For quick shipping and shipping of materials that are dangerous

We cannot ship materials within two days if they contain dangerous materials or if they are being sent to an Army Post Office, Fleet Post Office (another type of army mail) or to a Post Office Box. If this is acceptable then continue, if not then change the address.

Basically you cannot ship something in express mail if you want to send something potentially dangerous or want to send something to someone in the army or using a post office box.