Online lessons are very similar to private lessons.
The student sits at the piano with a screen in front of them. The screen can be a computer, a mobile phone, a tablet, or even a TV if you can cast the lessons to the TV screen.
Classes are arranged in short videos and should start with explaining how the lessons work.
The first actual lesson will teach you how to sit, what the notes are called, finger numbers, and other simple but essential items of information that are so important to a beginning student.
Lessons then go on to simple elementary music and how it relates to the piano notes.
As your lessons progress and your abilities increase, the music will become more advanced as you play simple songs.
Repeating a lesson helps tremendously to overcome anything you cannot fully understand. Good teachers will provide excellent support where you can contact them and discuss your problems. Some good teachers will even do a short Zoom call with you to hear you playing and sort out your problems