The behavior of a computer program can be influenced by its commands, arguments, and options. These terms are often mixed up, so let's start with a quick introduction.
Commands tell the program what to do. An option tells the program how to do it. Arguments usually follow an option, like a filename, or a target. It provides a value to the particular option that is used.
The Lynis tool requires a minimum number of parameters to run. If you are using it for the first time, just run 'lynis'. It will provide basic information and shows typical commands and options for its usage.