Since you are going to take courses, so what you need before that is to learn what will not be available in the program: business or investment sense.

Read something such as behavioral finance and general stuffs about financial markets to get business sense, which you will never learn from school, but is actually most important. Many good investors never majored in investment at all. This means that something beyond school is much mort important than a few books. If you have nothing to pick up, read newspaper’s investment sections. YES read newspaper.

Also, you are majored in language, I would suggest that avoid any technical stuffs, which are probably not useful for you any way, at least now, unless you feel  not confident of your math and you need it for the program later on. Any financial engineering stuff such as Hull's book is probably not suitable for you. But you do need some statistical concepts later as part of investment concepts, Again, do not get too much into it, because you are unlike to master it nor actually use it.

It is the investment sense that makes you an investor, so start to get or enhance that sense if you still feel uneasy about it. Keep in mind, most investment professors do not invest.

Hope this makes sense to you.