It is used to execute a command whilst suppressing normal shell function lookup.
Built-in functions take precedence over programs when resolving the name of a command.
A user may suppress the lookup of built-in functions in order to execute a program with the same name as a built-in function.
In all other circumstances the command will be processed as normal.
In the following, the ls command is run without any shell functions or aliases that may exist with the same name: