<p>Most colleges these days want to see that you have taken the same language for all four years of high school. If you want to get credit in college you will need to take the AP exam, if you are good it may be beneficial to take the SAT II as well. That being said if you are planning to self study a language in high school instead of taking one for credits you may experience issues when you go to apply to college.
You could mention it on your resume, under a skills category. Something along the lines of “Proficent in _____.”</p>