Including the British pound - until decimalisation in 1971, the abbreviations for pounds, shillings and pence were Lsd (with the L often having a single or double cross bar) from the Latin libra, solidus and denarius respectively.
Sorry. If I had explained, I don't think that it would have been unsubstantive. But I didn't. So anyway, to the point.
As the sign of balance, symbolized by scales, Libra is certainly relevant to money. But the name is also a riff on liberty/liberation aka freedom. And that's the sick joke, because Libre will be totally under Facebook control.
Means pound in Spanish. As if it holds any weight in the real world. Alt Timeline: Zuckerberg becomes POTUS in 2018. By 2020 he becomes POTKW and conquers all countries with just the information he knows about people on Facebook.