Every protein is made up of a sequence of amino acids joined together. These amino acids interact to form shapes, these shapes fold up on a larger scale to become complex 3D structures, basically the building blocks for all life on our planet.
There are an unimaginable number of ways for proteins to potentially fold themselves. So figuring out how they quickly fold themselves in a consistent way is very tricky. Currently, there are over 200 million known proteins, with many more found every year. Each one has a unique 3D shape that determines how it works and what it does.