The word is intended to be a nonsensical word that sounds impressive and elaborate. It's often used humorously to express:
* Something wonderful or amazing: "That new restaurant is supercalifragilisticexpialidocious!"
* Something very complex or difficult to explain: "The scientific theory behind this experiment is supercalifragilisticexpialidocious."
* A feeling of excitement or joy: "I'm feeling supercalifragilisticexpialidocious today!"
So, while it's not a real word, it has become a fun and widely recognized way to express a range of emotions and ideas.