what type of benefits othe than those from the ollege come with being a foreign language professor
Some lead study abroad trips with current students or alumni of the institution. These trips can be a week or two or a semester or more. They allow for travel and immersion in the language and culture and can be very fun as well as educational.
Some get involved in bringing speakers from the foreign country to their campus, for their own department or for other departments within the college/university. As an example, a German professor might bring in a poet or novelist to speak to German language students; or, they may help find a German business leader to speak to business students.
Some may get asked to speak on topics in culture or politics for the countries of the language(s) they teach. Newspapers and TV news programs (and other media) need experts when something meaningful is happening in the country where the language is spoken; e.g., if there's a significant cultural event in Japan, a professor may be asked to put it into context of Japanese history or similar cultural events.
A professor of mine in graduate school was approached by a film director to assist with both the language and the culturally appropriate non-verbal communication in a movie.
Also, you can investigate job boards like Indeed to see just how in-demand some languages are. I have seen listings recently that require/prefer applicants proficient in languages like Korean, Mandarin, Spanish, and German - among many others.
Anything dealing with being a learned person in any field that requires knowledge and skill has its benefits. During the few months to a year where you can take off you can travel and go research and teach in different regions and places. Your major benefit is employment all over the world. Your greatest benefit is arming the youth with strategies, methods and self empowerment.