Is it beneficial to learn a specific programming language even if that language isn't typically used at your firm?

I am currently an MS Finance student learning R for some of my courses. I am, however, not the most capable at R and was debating taking an R course in my free time to strengthen my skills before entering the workforce. However, it seems Python and other programming languages have much wider adoption; would it be better to learn another language, or is there some value to strengthening my R skills, seeing as I am already used to it, even if R isn't typically used at my firm? Follow-up question: Do companies typically let you use whatever programming language you want to get the job done, or do they expect you to learn the particular language they use?