Bitcoin revolutionized the world by introducing a system where the security of one’s funds were secured without having to trust any participant on the network. It uses a shared ledger called a blockchain that simply records a history of transactions that have occurred. With Bitcoin, it shows explicitly that a certain amount of Bitcoin was transferred from one address to another. It is completely transparent.
Monero functions the same way, except the information stored on the blockchain is indiscernible to an outside observer. Monero uses a different mining algorithm to secure the network called CryptoNight. Through this process, Monero provides the same services as Bitcoin, and does not rely on any trusted party.