A 'hacker' is a term so generic and overused that it almost has no meaning. If I had to define a hacker I define it as someone with a deep understanding of how computers work, with a drive to constantly learn more.
This is similar to a car mechanic. Generally if one has an interest in cars one will spend a lot of time trying to figure out how they work, taking them apart, and making improvements. Eventually they will build up more and more knowledge. There will be no point at which they are suddenly a mechanic (ignore professional mechanics for this analogy, as realistically no one is going to employ you as a hacker).
If you have a deep interest in how computers work you will seek out knowledge and eventually develop an equally deep understanding. If you simply want to learn what is necessary to protect yourself online, then there are plenty of simple guides online that you can search for. In either case, realize you will never be done. New technologies and attacks come out every day.
The whole of human knowledge is at your finger tips. Just start searching for how things work. Start with an article like this:
Read that, and open up in new tabs anything you don't understand or that sounds like it might be interesting. Do that with every article.
Here is a great site for tech Q&As:
Read through a lot of questions. Use the search function. Here is a good search to get you started: