What does nyan mean?

I'm curious, could you please clarify what "nyan" means? Is it a term specific to the world of cryptocurrency or finance? Or is it perhaps a reference to a popular internet meme or slang that has somehow become intertwined with these fields? I'm eager to understand the context and significance of this term, and how it might relate to the broader landscape of digital currencies and financial transactions. Thank you for your assistance in shedding light on this mystery!