Trying to grasp the technology behind the bitcoin blockchain and why so many things happen the way they do has become quite a confusion to me, I read about bitcoin blockchain and I saw that nodes help to validate transaction and all of them or most of them must agree something like voting that is been done before they store or validate a transaction, and I am a bit confused about this or how it works, in fact instead of going into much detail on what I know, I wish someone would help me out by answering my questions that help enlighten me, I've also come across a recent topic about nodes but it doesn't quite ease my curiosity.

I don't have the best english please mind me 🙏

1. What is a node and what is its function

2. Is the node a protective counter measure to protect the blockchain from scammers

3.if the nodes act as a validator does this protection still extends to exchanges and why are they being hacked, cause I know that bitcoin is actually stored on a location in the blockchain and if it's anti bodies are nodes, how do some exchanges still get hacked ?

Please is me been confused, don't mind me for asking this kind of question, you can provide me with a link for me to read about it if you have one, I'll really appreciate.