"Programming in college" is pretty broad, but it seems like you're thinking about pursuing a computer science degree or similar in college? If that's the case, the programming languages taught first at each college will vary. For example, UCLA starts with C++, while Berkeley starts with Python. If you already know what language your target school starts with, great! That'll be the one to learn.
However, it's likely you don't know that yet, which would be fair. In that case, I'd recommend learning some kind of C-family language (most programming languages fall into this category). What this means is that the languages' syntax (the "grammar," if you will) is pretty similar between each other, so the skills and conventions you learn will also be easily transferrable. I learned Java in high school, because my school offered the class, but I understand not everyone will have had that opportunity.
That being said, college courses typically at least start by assuming you have no knowledge of the language in question, and will be designed around you picking up the language as you go. Learning programming before entering college is good to familiarize yourself with the paradigms that exist, but don't feel that you need to know everything or else risk falling behind. The hardest part of programming, I've found, isn't learning new languages, but rather learning how to use the tools available to you to solve problems.