A no op (or no-op), for no operation , is a computer instruction that takes up a small amount of space but specifies no operation. The computer processor simply moves to the next sequential instruction. The no op is included in most assembler languages. It may have a label and can serve as a placeholder for a useful instruction to be inserted later during code development.
The New Hacker's Dictionary reports as a derivative meaning "A person who contributes nothing to a project, or has nothing going on upstairs, or both. As in 'He's a no-op.'"