What role do relevant (!) foreign languages play in grad admissions? Say I want to apply to a program like Comparative Literature or Classics, where it is required that during the program I will pick up at least X languages and will have to sit language exams etc. but it is not required in any way to already speak these languages at admission to the program.

Question:

Will stating that I already speak relevant language X (because it's my native language say) or have already studied language Y for two years (because I want to focus on writer A who wrote in language Y) be an advantage? And if so, how much of an advantage will this be?

I guess it is obvious that schools will care mostly about the quality of the candidate's research etc. but what role would knowing (relevant) foreign languages play here? 

PS: Note that I am talking only about foreign languages relevant to the program here. So for example latin for a classics program, or german &amp; french for a comparative literature program where someone wants to focus on precisely these languages.
In Art History, this depends greatly on the language and the area of study. For example, an individual who wants to study Italian Renaissance would likely benefit from knowing Italian, French and German. These are such common languages and the Art is so well studied, that knowing them in advance is likely of little value in regards to admissions. On the other hand, if you want to study ancient Hindi art, then demonstrating that you know Sanskrit could be valuable for admissions since the university may not routinely offer the language and you likely need to be able to read it to write a reasonable proposal.