Recording the network-approved transactions in the Blockchain is called mining. This is done by Miners.

Miners are computers, but these are not ordinary computers. These are often specially designed to perform nothing other than mining Bitcoins. They do this by solving mathematical puzzles (hence the name crypto).

Solving such a puzzle requires a lot of computing power. The computer must also compete with other Miners. Which computer solves the puzzle first may therefore add its block to the Blockchain with approved transactions and receive 12.5 new Bitcoins as well as the transaction fees associated with the transactions in the block. So this whole process is actually a bit like the digital version of mining gold from a mine. With good material, you win more gold.