Analyzing and Visualizing Data with Power BI is a great course on the Edx.org platform. The course is free (although there is a fee if you want a certificate of completion) and is well structured. The course is a great resource for PowerBI newbies and beginners. Even professionals with some experience with PowerBI would benefit from this one.
The course consists of learning modules, knowledge checks and labs. Plan on spending 12-20 hours completing the course.