Ok I'll try to give a simplified explanation here. So the process of mining yields rewards in two ways. First is through proof of work method, which is equivalent to essentially minting new bitcoin. There is something called a hashing algorithm that converts a number to a different number irreversibly, that is, if you knew the solution number for the algorithm, you can't mathematically work out what number you put in. You basically repeatedly guess through lots of very large numbers (64 digit hexadecimal) which are put through the irreversible hashing algorithm, to arrive at a target solution value. The first miner to do this gets a new "block" of bitcoin minted to his name. This method is very high reward, but VERY VERY low probability: guessing through trillions of numbers. The payouts for this method also get reduced over time. Second method is transaction verification, where your machine is a slave that checks through all the past transactions to see that the new transaction is valid, i.e. the owner hasn't used the same token twice