what does this code actually do for bitcoin? I just saw it for the first time and was amazed by the many code. I want to know what the code means. does it have a real function or not?
This is the github repository for
Bitcoin Core. Bitcoin Core has several functions, one of which includes performing the operations of a full-node, i.e validating transactions and the blockchain, as well as communicating with other full and or SPV nodes. It can also operate as a Bitcoin wallet, which I assume you have some understanding of.
Bitcoin Core is a direct successor of Satoshi's original bitcoin client, although it's certainly not the only full node software available.