The code above is a smarty function for building date-based drop down menus. However, changing that code will do nothing for you as "Year" isn't displayed. Rather, PHP uses that to build the dates. It is used on the signup pages where dates are asked for (if you have age turned on).

It would really help you to learn a bit about PHP programming (the basics). By doing this, it will save you a lot of frustration trying to find things that you can translate. There are many things that "look" like they are displayed in the browser but, in fact, are not.