Course descriptions often list skills and hours. Look at what you will actually practise so you can judge whether the course fits your goal.
Find a sample lesson or assignment and check how closely it resembles work you want to do. If you need to build a simple website, look for a project that takes you from a brief to a usable page. Check prerequisites, feedback and the time needed to finish the exercises.
Set a small milestone before enrolling, such as completing one project you can explain to someone else. Check current access and cancellation terms with the provider. Give the work a realistic place in your weekly calendar.