Like you were five: you ask your best friend a question, she doesn't know the answer, so she asks another person, who doesn't still know the answer but know someone who does, they get the answer, pass it back to the person before until it gets to your best friend. You only interacted with your best friend, nobody told you about "the others".
To have a distributed system you need to have more than one component connected by a network resulting in a single system to the user. These components talk to each other exchanging messages.
The internet is the biggest example of a distributed system. The web is another example of distributed system: you ask something to a browser, they get the answer somehow by talking to various entities linked by a network, they get you the answer back. A telephone network is another distributed system.
Let me know if there's something you're unsure about. I'm happy to expand.
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