Training modes

Morse Flyer's practice is organized by what you are training: receiving (Copy), sending (Key), or working other stations (Contest). If you are starting out, start with Copy — sending is much easier to learn once the sounds already mean something to you.
Copy — learning to receive
Copy modes send to you and ask what you heard. Listen and Type and Multiple Choice suit early days, when recognition is still forming and typing a guess is less discouraging than silence. Callsign Copy moves to realistic material — real callsign shapes rather than isolated letters, a noticeably different skill.
Key — learning to send
Key modes ask you to send a character or a word and judge what you actually sent. Key Lesson introduces characters a few at a time and stays with them until they are solid. Key Challenge mixes what you already know and pushes the pace. Free Key lets you key whatever you want. Any valid character works. Listen and Key closes the loop: hear it, then send it back.
Flight modes — practice with a clock
Timed flights put the drills in the air: Race, Practice, Endurance, and Parrot, each available in keying or copying form. The clock is the point. Accuracy under mild pressure is closer to on-air conditions than accuracy with unlimited time, and the difference shows up fast. The time limit makes the score more meaningful.
Audio Trainer
A focused listening mode for building recognition without the game around it. Useful when you want repetition rather than a session.
Field Day Runner — the contest simulator
The most complete simulation in the app: you call CQ, stations answer, sometimes several at once, and you work them for a real exchange under realistic band conditions. It has its own page, because it is closer to a contest simulator than a drill. If you can do this, you are probably ready to join in on a radio field day event.
Tutorials
Separate guided introductions exist for straight key and for paddles, covering how to hold timing and what the app expects, before you start scoring anything. This is pretty basic.