It's a word that actually refers to a very simple thing.
In computer systems, metadata is basically the information of the file (i.e. file size, date created, date modified, etc.)
Metadata is—for the most part—specific depending on the type of file. For music and video files, it can include information such as length, bitrate, artist, title, resolution, etc etc.
"Before sharing the document, make sure to remove any sensitive metadata such as author names, revisionhistory, and comments to protect the privacy and confidentiality of the file"
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.
A lighthearted reaction upon receiving disappointing news of some sort. Usually something that isn't a particularly a big deal, esp. when it primarily affects someone else - sort of a mild schadenfreude. Sometimes doubled or tripled, and possibly said in a sing-songy voice for added comedic effect to imitate a muted trumpet, which is how the meme originated.