Proving I am fluent in another language outside of school.

I have so far taken 2 years of Spanish. However, I am fluent in Turkish. I know I cannot just tell a university that I can speak another language. Is there some way to get it certified or proved. It is not a common language like Spanish so I cannot just skip to Spanish Speakers classes in my school or online. Is it ok if I only take two years of Spanish knowing I am fluent in a different language? Thanks!

How many years a high school language required for admission has little to do with whether or not you are fluent in another unrelated language. The language requirements to graduate from high school are set by your high school, and for admission to college by the school you are applying to. If your resume has a skills section, you could list the language you are fluent in there.

Yes you can. There’s a section on the application where you list the languages in which you are proficient. No “proof” is required.

That’s really going to be specific to the university, so you should ask them directly. However, in most cases, if the university wants more than 2 years of foreign language study, the expectation is that at least part of that study occurred in HS or beyond.

When it comes to college admissions you do not need to “prove” you are fluent in another language. You just say you are. Usually they are other hints in your applications that will corroborate it. For example your family comes from the area that this language is spoken etc. If there is absolutely NO connection with you and the spoken language I would add something in the common app to explain how this language fluency is acquired. That addition is not “proving” anything but it makes for an interesting story something that can only be a positive in your application.
Now when it comes to official requirements that is entirely a different matter and I agree with the previous poster. If you want to explore it further you should talk directly to your high school or to colleges that you are applying to.

Does your HS offer independent study? Would they allow you to find a way to officially study Turkish? If you live near a university, see if they offer Turkish, and if you can test into a higher level course. One semester studied at a higher level would demonstrate what you need. Foreign language requirements when applying to college come in 2 forms: number of years studied, or level studied. You would need to ask the individual admissions offices which applies.

How strong are your reading and writing skills?

Foreign language is looked at as a core academic class by most colleges. Look at the common data set of schools you are interested in applying to and see if two years of Spanish will be sufficient. Typically top tier colleges want to see 3 - 4 years of foreign language (up to level 3 or 4) taken in an academic setting.

You could get a CEFR certificate, they are generally the international standard for foreign language proficiency.

FWIW, the Georgetown U. summer program for HS students offers Turkish for college credit.
https://summer.georgetown.edu/programs/SHS04/college-credit-courses/coursefilterlist

(The Turkish II class starts on July 9th, this year. And you’ve got another summer before you apply to colleges. Maybe you could get the Turkish credit and also take something else that interests you.)

And NYU offers a testing program. http://www.scps.nyu.edu/academics/departments/foreign-languages/testing.html

Getting your level of Turkish evaluated and certified can only help you. Is there a cultural institution that may be able to certify you?

I have no clue I am trying to look into it but nothing I can find so far. Maybe a university who offers turkish?

What state do you live in?

Another poster gave you the link to NYU’s certification program. That’s the one a lot of universities I’ve worked with recommend. Look into that one. It’s accepted at most of the unis I know of.

I’ve also seen some unis have you speak with one of their professors who is fluent in that language, to prove your fluency. No, really! You have a brief conversation on the phone with that professor, and it’s apparent quite quickly if you’re fluent or not. Not a lot of unis do this, but some do.

Another option is to take an upper level course in Turkish at a local university, or online via a reputable university. That not only proves your knowledge, but also might waive you out of foreign language once you go to university for your degree. What you’d normally do is take the final course in the language sequence (for example, Turkish 4), or a course beyond that.