It’s easy to learn Flask if you are familiar with Python and web development using other Python frameworks or having familiarity with MVC or related topics. You can learn Flask easily if you have knowledge of Bottle since it was developed as a spoof for bottle.
Only, if you are a beginner, it takes time to learn Flask because you need to understand understanding HTML and templatization better before understanding the framework itself.
Also, watch this video to create a simple application in Python Flask: