(I’m not a mentor for this course. Here are some general tips)
Click on the cell that contains the comment “Test your code!”, and then click the “Run” button in the main toolbar.
The [*] next to that cell means you haven’t run that cell yet.
“Line 19” refers to the line of code in the script that the grader uses - not to your notebook. So the message isn’t that useful, except for the “invalid syntax” part.
Somewhere in your notebook, you have a line that the grader doesn’t like.
Sometimes this can be as simple as putting a closing parenthesis ‘)’ on a line by itself.
An isolated closing parenthesis is fine by Python standards, but the grader tends to not like it.
That cell doesn’t generate any output, it just imports the “test_your_code” module.
But after you run that cell, it should have a number inside the square brackets.