How many transactions are there in one block

How many transactions are there in one block

What I understand:

When a transaction is made , miners compete to validate it and create a hash . If one miner creates the hash and more than 51% of miners agree on the validity .Then the a block is added to the blockchain.
Am I right?

My doubt:

1)When a block is added it contains one transaction that is validated or more?

Thanks.