How do we transfer money thousands of years ago, when we live in small villages, know and trust each other? We easily barter, as we do with cash now. But when money is transferred online, this will be a bit tricky. Banks and credit card services solve this problem with a 'ledger system' ('cash system') -- which stores the account history and shows who owns what.
When John made an online money transfer from one person to another, it was the bank who made the transfer from John to someone else. John can not do it himself because there is a risk he cheats - he can copy (copy) and paste (stick) the digital money (because it's just a number on the computer) and send to two different people. So we trust the bank to send money and make sure only one person receives the money. The bank can cheat, but we believe they are not cheating.
If a transfer takes place at the same bank, it is easy to do. But if the banks are different, this will be a little tricky because they may have different cash systems and need to be matched. Therefore, they charge a small fee, and usually this transfer takes a little time. When these banks and financial systems come from different countries, things get more complicated: different languages, systems, currencies, and more people have to coordinate and so on, so the cost and time of transfers grow. That is why the current financial system is so complex. The system is a huge mess of cash systems in the world.
Bitcoin changed all that. With what? Bitcoin is a cash system that syncs across the internet, so everyone can access the same cash account in real time regardless of who and where it is. The result? Money can be transferred from one party to another without unnecessary delays and costs. Like when money used to be used, before the world became so big and complicated.
Bitcoin payment system used for what? The answer: whatever you use with regular money: send to friends and family - both local and overseas, buy goods online, receive paychecks, and so on.
Bottom line:
Bitcoin is a faster, cheaper, and easier way to transfer money.