In a nutshell: A miner finds a valid hash, broadcasts the candidate block + hash to the network, nodes verify the candidate block, its contents and the hash, validate the block, add it to their local copy of the blockchain, and broadcast it along to its peers.

The miner managed to add a new batch of transactions through the process finding a valid hash, which is a computational and energy-intensive task. For his efforts (and incurred costs) he is awarded the newly created bitcoin from the block he broadcasted, called "block-subsidy", as well as the fees from the transactions contained within the block, which together make up the "block reward".