Can somebody please explain what is tweening and how to do it?

Tweening is a major part of making that illusion look real. Tweening in animation is a short for inbetweening, and it's the process of generating images that go between keyframes. Keyframes are the images at the beginning and end of a smooth transition. i got this from google lol

also, happy new year!

Inbetweening or tweening is a key process in all types of animation, including computer animation. It is the process of generating intermediate frames between two images, called key frames, to give the appearance that the first image evolves smoothly into the second image