The Libra Coin whitepaper has this hide-and-seek writing style that makes it few things explained in a confused way. I’ll try to summarize them here.
The starting point is an exchange-traded fund (ETF) pegged to a basket of currencies (USD+EUR+…), but there aren’t details on what kind of rules this fund should follow. Basically, there aren’t details at all, only a clear statement that if there’s profit from this fund, it will go to members of the “Libra Association”, not to owners of Libra. This association and the fund will be based in Switzerland. The ETF value will be divided into tiny shares, or vouchers, or tokens, called Libra Coins. So the Libra Coin will have a known value that depends on the ETF.
The “Blockchain” part isn’t really blockchain, but it’s a centralized database where writing is permissioned from members of the Libra association (entry fee 10M$, invitation only). There actually are some sugar-the-pill details that makes it look like an advanced distributed system, but they’re minor and pointless and everything could have been done in the same way in the nineties.
Libra coins can be moved through any “accepted by the association” wallet, but only the Calibra wallet will be integrated with Whatsapp or Facebook or Instagram. Obtaining the Calibra wallet involves KYC/AML.
Marketing sweeteners abound in the whitepaper(s), they say they would like to become a real permissionless cryptocurrency in five years, but first they would like some problems to be solved. Unfortunately their list of problems is the entire specification for a new incredible cryptocurrency. Stonk. They also point out that Bitcoin consumes a lot of energy “We did not consider proof-of-work based protocols due to their poor performance and high energy (and environmental) costs”, which is a reasonable criticism, but the association doesn’t include any environmental friendly member. Sbirch.
TL;TR Libra is a voucher managed with a centralized database, whose value depends on a huge ETF managed in Switzerland and whose association will allow only Facebook to move the coins. And some crypto-related buzzwords for the lols.