Why Headphones have left and right?

Sound moves quite slowly. There is a delay that a brain can detect a time difference between the sound arriving at your left ear and right ear which is called interaural time difference.

To get the live listening experience sound engineers mix various sound to one channel or other so you hear different parts and you get closer to live experience.

What is L and R in stereo?

Stereo music is recorded with multiple microphone which gives these illusions that sound is coming from different directions, and Headphones provide the best way to experience that illusion as they push the music directly into each ear. So it is essential to put on your earphone to the correct ears so that you can experience the music as the musician recorded it.

Does right and left really matters on Headphones?

If you want to have a live experience of any of your favourite music then you must have to wear it right.