As aforementioned there are different kinds of systems / applications, e.g. web development, phones apps, real time applications, ERP, operating systems, etc. All of these would use different programming languages and platform for the coding.
I would suggest you could choose Computer Science as your major to learn about all the fundamentals and start programming in different languages first. The courses will also give you an overview of different kinds of coding and platforms. You can then decide which areas you would like to focus when you start your careeer.
Hope this works! Good Luck!