A Lottie is a JSON-based animation file format that enables designers to ship animations on any platform as easily as shipping static assets. They are small files that work on any device and can scale up or down without pixelation.
You can see the official website.
If you want to use wordpress you need to know this:
LottieFiles for WordPress is the easiest way to add Lottie animations to your WordPress website using the Gutenberg editor.
This is a Lottie file:
74321-3d-education