@mnopstuv5000,
I am a programmer. I don't know what the term "administrator in e-commerce" specifically refers to. The term "administrator" is often used to mean "system administrator".
The system administrator is the person who takes care of the hardware and the networks. They do everything from buying new computers and boards, to buying, installing and maintaining software. They also keep the network running and talk to the network provider. They start systems up, and are the often the first person contacted when a system goes down.