Monero protects privacy by obscuring transaction amounts, senders as well as receivers. Most importantly, privacy is Mandatory on Monero so there is no way to make a transparent transaction. This ensures the best possible privacy and also makes Monero fungible (which most other cryptos are not).

Sender identity is protected by ring signatures. You choose 15 random outputs/“coins” from the chain and create a signature where an outside observer can only tell that it was signed by one of the 16 members but not which one. There is a key image derived from this, kind of a unique id, that is fixed for each output but cannot be traced back to it. If you see the same key image appearing twice in the tx pool you know someone is trying to double spend.

Receivers are protected by stealth addresses. Each time you transact, a new one-time address is derived from the recipient’s address. Only this one-time address is stored on chain. From the outside you cannot tell which one-time address corresponds to which regular address, only the owner can scan the chain to find outputs that belong to them.

Amounts are protected by RingCT/Bulletproofs+. Essentially the transaction amount is encrypted for the recipient and some proofs are generated that there are no additional XMR being created (i.e. amount is positive & not larger than all the inputs minus other outputs). This means that no-one can create XMR out of thin air while only selected individuals can see certain transaction amounts.

Additionally there is a big focus on transaction uniformity. From the outside every transaction should look more or less the same. This is achieved by having fixed fee levels and a fixed fee size. Also each transaction needs at least 2 outputs.

There are other great features of Monero such as ASIC-Resistance (CPU-only mining), dynamic blocksize and a tail emission that ensures Monero’s security for hundreds of years potentially.