Learning is the act, process, or experience of gaining knowledge or skill. In order to gain knowledge, someone else has to share knowledge.
As the Scrum guide states, scrum is lightweight, simple to understand, and difficult to master. Is this true? What does this imply?
Compared to project management methods like Prince II or development methods like XP or RUP (although these frameworks and methods may not be directly comparable), the Scrum framework is concise and straightforward. To describe a framework in 17 pages and summarize it in a simple picture that depicts all components (events, roles, artifacts) entails simplicity. So yes, the framework is lightweight, and as William Golding said, “the greatest ideas are the simplest.”
Shuhari, the Japanese martial art concept that describes the stages from learning to mastery, helps describe simple to understand, difficult to master. The word shuhari roughly translates to "first learn, then detach, and finally transcend." Indeed, shu is reached relatively easy with Scrum. If you take an hour to explain the elements of the framework, you will understand their meaning and interactions and will be able to follow these rules. So yes, the framework is easy to understand.
You can compare Scrum to chess for that matter. It is easy to learn the rules of chess—which piece is allowed to make which move, when you win, when you lose. However, when you play against an experienced opponent, you quickly discover that you have no clue how to play the game properly. In order to win such a game, one has to train over and over. Gain knowledge and skill by trying, failing, and trying again. So yes, it is difficult to master.
To reach the ha or ri stage in Scrum, you have to practice and learn. One must comprehend why each component is in place and how it delivers value as an individual element and in relation with the other elements. To excel in Scrum requires discipline and perseverance but then one will truly harvest the benefits.