Flexi discs are thin, floppy records that can be bent and folded like a piece of paper. They're made of a very thin sheet of vinyl that's been printed with music or other audio. Imagine a paper plate, but thinner and made out of vinyl instead of paper.
Because they're so flexible, flexi discs can be stored and shipped in ways that traditional records can't. They're often included in magazines or other publications as a way to distribute music to a large audience.
To play a flexi disc, you need a special turntable that has a smaller spindle than a regular record player. You place the disc on the turntable, and the needle on the tonearm reads the grooves in the vinyl to play the music.
Flexi discs aren't as high-quality as traditional records, so they don't sound quite as good. But they're an interesting piece of music history and a unique way to listen to music.