From the source below:

You must know at least 3 of the 6 official UN languages with English and French typically at the core. The third language would then be either Russian, Arabic, Chinese, or Spanish.
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How does one go about becoming a UN translator?

Obtain a university degree and gain some experience with translation. For example, take some translation courses.
Should not be older than 32 years old.
Pass the examinations: a written exam and interview

The Exams

Most Americans sit for the exam in New York City (NYC). Exams are also offered in Geneva, where core competency must be demonstrated in French. The exams are not given every year (depending on staffing needs) and they are very competitive. The UN may hire a handful of people out of hundreds of applicants. But again, the exact number hired depends on the demand.

There are two components to the written examinations: translation and précis-writing in one of the five UN languages. Précis-writing involves not only translating documents from one language into another but also summarizing the contents. A typical précis-writing assignment requires the translator to summarize the proceedings of a committee meeting, capturing the gist of what was discussed without losing the accuracy of the meaning, but more succinctly than in a verbatim transcript.

Précis-writing exams are usually given over two days, and translators for all the UN locations (e.g., NYC, Geneva, Nairobi, Bangkok, or Santiago) share the general job description. Committee assignments mirror the range of specialties that constitute the UN’s work from political (mostly in NYC) to social, economic, financial, administrative, scientific, or technical.

Those who pass the exams are then invited for an interview before a hiring decision is made.

Translators is for written language. Interpreters are for spoken language.

Do you have an undergraduate degree? Do you know any sign language?

You need a masters to work with deaf kids, in special ed. The best schools to go to are Gallaudet University in Washington DC, which is a university for the deaf, but hearing people can get into the graduate program. Also, McAllaster which is in Maryland is another great school. Look for programs that focus on deaf education only. That’s if you want to teach them.

If you just want to become an interpreter.. check with your state schools and find out the requirements.. I know that some states have stricter requirements than others, also ask around in the Deaf community in your area where the best interpreters in your area trained.. or even get in contact with local sign language interpertering agencies.