This assertion allows you to print out (in test reports) information.
It can have two sorts of values. The first is a normal string value. An example of that would be to explain what a specific WHEN loop is being used for. Similar to when you write comments in code.
The second is useful for test debugging and analysis. You can pass variables into the comments. An example use of this would be to print out the product ID being used in the current loop of a test.