In Simple Words
When you hear “Bitcoin mining,” you might imagine miners searching somewhere for bitcoin. In reality, they do something different.
They gather transactions and try to create the next block. Their computers compete through a process called Proof of Work.
The miner who succeeds first proposes the new block and may receive the reward. But miners do not decide on their own what is valid.
Nodes check that the block follows Bitcoin’s rules. In simple words: miners propose blocks — nodes verify the rules.