I am a high school student, for the past few months I have been deciding what field I would like to pursue in college but I am still on the edge between Veterinary studies, Engineering, Law, and Marine Biology. I don’t know how to decide, does any one have any helpful tools on how to decide a major?
That’s a pretty wide range 
The only way to know is to do some soul searching. Spend time really pondering about it. Do some real research. Engineering is a field where you’re going to loooooove math! Law is a field where you spend most of your time talking to clients and filing paperwork, from what I hear, it’s pretty dull the vast majority of the time. Outside of medical, biology is not a field where you’re going to make a lot of money, unless you major in something like biochemical engineering.
Law and veterinary studies usually aren’t majors at the undergrad level. Some colleges have majors in animal science or something related to that, but not veterinary studies per se.
The traditional way to choose a major is to take some classes in your freshman and early sophomore year and see what you like. That gives you some chance to try things out and see what you actually enjoy. In this current environment of having to apply separately to the engineering school at many universities, it’s hard to do that if one of the majors you are considering is engineering. One option is to apply as an engineering major and take a few classes outside of engineering to be sure as well.
Law doesn’t have to be dull - it depends on what you do. There are private solo lawyers and lawyers who work at big law firms, and they likely do spend most of the time talking to clients and handling paperwork - but that doesn’t necessarily have to be boring. Some lawyers work at nonprofits or civil rights firms doing that kind of work; some work at government agencies; some work at big for-profit employers. I work with some lawyers who help us navigate the legal requirements behind the research we do at my company, for example.