You will need a list of learning outcomes for your course, to explain to learners what they could expect to learn from your course. You won't be able to save the Edit settings form for the course without something in the Learning outcomes box. This is because Learning outcomes are displayed on the course home page and are required on a Statement of Participation.
It is helpful to start learning outcomes with a sentence which says something along the lines of 'As a result of studying this course, learners will be able to' followed by the list of learning outcomes. Learning outcomes are not a course description. A good way of writing learning outcomes is to articulate them as active and think about them as what the learner will be able to do as a result of studying your course, so use verbs at the start of each learning outcome – see the useful guide on learning outcomes by Bridget Winwood and Alison Purvis How to write learning outcomes which are SMART (specific, measurable, achievable, relevant and time bound).