It is one of the coin as the privacy token which is bitcoin-forked. It uses zero knowledge succinct non-interactive argument of knowledge. Miners can verify a transaction without knowing who has sent or received. So it basically protects the privacy unlike a normal bitcoin transaction where one can easily see the sender and receiver address and through some sort of social engineering and studying the patterns one can be able to identify a person too. So in order to address this issue we have privacy token like Zcash. But the big problem about privacy tokens are that there are so many available now, so facing a competition within themselves.
I think that Zcash has an OK idea behind it. Basically, it uses zero knowledge proofs to shield information about users, or to quote " It enables one party to prove to another that something is true, without revealing any information, apart from the fact that this specific statement is true. "
Although effectively just a copy paste of Bitcoins blockchain, It seeks to remedy the issues that bitcoin has in terms of price and privacy. The problem is that it faces stiff competition from both sides - the privacy led coins and the non-private and that it doesn't really do anything else particularly special. There is literally coins and projects dropping onto the market faster than anyone can keep up with (there is currently 4325 coins listed on coingecko) and many will fall by the wayside as new and more innovative coins join. If it doesn't find it's niche in the market, My fear with Zcash is that it may be one of those to fall.