Ronny De Winter completed this course, spending 2 hours a week on it and found the course difficulty to be easy.
Google sheets is an excellent spreadsheet application. No need to buy an Excel license, use google sheets for free, it has >90% of its features and more.
Google sheets are quite intuitive, they work similarly to excel. No doubt you can find how to use a specific feature without taking this course. This course, however, gives you an extensive overview of all the features with examples, including features you won't easily find in other spreadsheet applications like realtime collaboration, integration with google translate and google finance, and much more.