The essence of Bitcoin’s use of asymmetric cryptography is that bitcoins are sent to public keys and spent with private keys.
On a similar note to how the keypairs work in communication, a user can broadcast their public key — the Bitcoin address — to the entire world, but they must keep their private key secret as it can be used later to authorise spending from the address.
For example, if Alice wants to receive bitcoin from Bob, she starts by sending Bob her public key — the Bitcoin address. Next, Bob uses his private key to authorise the spending of bitcoin from an address he already controls. He then instructs the Bitcoin Network to move bitcoin from his address to Alice’s address by signing a transaction, offering a fee to a miner, and broadcasting it to the network.
Once Bob’s transaction is entered into a block by a miner, it is settled. Alice is now the new owner of the bitcoin and can authorise further spends with the unique private key corresponding to her address.