A mining reward is the payment a miner receives for adding a new block to a proof-of-workblockchain. It has two parts: newly created coins, called the subsidy, and the transaction fees paid by users. It is another name for the block reward, which is explained in full on that page.
On Bitcoin the subsidy is cut in half every 210,000 blocks in an event called the halving. Miners in a mining pool share the reward according to the pool's payout method.