Complex sentence: The term "copy" also refers to text in books, magazines (and newspapers), generally for the body copy, the main article or text that writers are responsible for, and not accompanying material such as headlines, which are written by copy editors.
Split into simpler sentences: The term "copy" also refers generally to text in books, magazines, and newspapers. It generally means the "body copy", the main article or text that writers are responsible for, as opposed to the accompanying material such as headlines, which are written by copy editors.