How does proof of work seal a new block?

"After transactions have been packaged, miners compete to find a block hash that satisfies the conditions set by bitcoin’s algorithm. They repeatedly add a randomly generated number called a nonce to the block data and calculate new hashes until one miner finds a qualifying result, typically requiring the hash to contain a specified pattern of zeros. The process is effectively a random lottery in which more hashing power increases a miner’s chances but does not guarantee success."