sadbehr , 10 months ago

Short: It completes a full 360° of the sun before the planet itself does a full 360° spin.

A few sentences longer:
In planet Earth human terms, we have defined one day as “how long it takes the planet to do a full 360 degree rotation”. Example: You spin a basketball on your finger and it does one full rotation.

A year to us is “how long it takes the planet to go around the sun”. Example: You hold a basketball out in front of you and you do one full rotation.