Monero is a cryptocurrency which focuses on privacy, fungiblity, and security.

With Monero, when you send an amount to another person, nobody can look at the blockchain to determine which account sent the money, the amount of the transaction, or which account it was sent to.

With Bitcoin, when you send an amount to another person, anyone can look at the blockchain to determine which account sent the money, the amount of the transaction, and which account it was sent to.

I don't want to go into a store, pay for an item with Bitcoin, and by so doing let the clerk and world know how much money I have in my account. But that's what happens when Bitcoin is used. That can't happen with Monero.

Website: https://getmonero.org

Comparison of privacy-centric coins: https://moneroforcash.com/monero-vs-dash-vs-zcash-vs-bitcoinmixers.php