Yes, there are! Many institutions release them, for example the Goethe institute or The Académie Française, and many other depending on the language. In Europe specifically, there is also a language-independent standard, the Common European Framework of Reference for Languages (CEFRL). It defines multiple "reference levels" of language competence, which you can get certificates for.
They are a proof of your knowledge, and can be used to enroll in universities, to apply for citizenships (not in every county), and in some jobs.
They do help if you work in certain fields, like multilingual customer service; however, often the companies will also (or instead) check directly your knowledge of the language before hiring you (usually by making interviews in the specific language).
Finally, they are not free and depending on the level you want to certify, the preparation needed may be demanding. So if you plan on taking an exam, try to research first what level will be useful or required for you - for example, with CEFRL, when one is required for a job, it will usually be at B2 or even C1, so getting a certificate at A2 will be of limited use.