While Alexa is a great tool for voice, it also has the ability to play other sounds, including the keys from a piano. This skill demonstrates the interactive nature of the device to quickly respond to notes spoken through the human voice.
For beginners, start with learning the musical scale. Provide Alexa note names, (A through G) to get started, and this skill will play them back. For example, say "Play F, or just utter the letter F" and that note will be played back to you. This can also play sharps and flats, as well as multiple notes at once.
After playing a series of notes, you can also say "Replay" and it will go back and replay the series of notes that you have provided.