The word “linguist” is ambiguous. Most commonly, it refers to someone who speaks multiple languages. A synonym for this is “polyglot”. Being a polyglot is a useful skill that can lead to a career as a translator or interpreter, and it can aid in many other careers as well. It is also personally enriching to learn a foreign language—it opens up a whole other window onto the human experience. In an ideal world, everyone would have the chance to spend some time living abroad, immersed in a foreign language.
In its second meaning, the word “linguist” refers to a profession or a practitioner: A linguist is a scientific researcher who engages in the systematic study of language, that is, a linguist does linguistics. We make observations about how language works, formulate hypotheses, test them, and revise our theories accordingly. We study language at all sorts of levels: linguistic sound systems, word structures, sentence structures, how words and sentences convey meanings, and how speakers use those meanings in the world. Some of us run experiments in the lab, some of us travel around the world to study understudied languages, some of us study language in the brain, some of us study how babies acquire language, and some of us study dialectal differences within a society. Linguistics is widely considered to be one of the core fields comprising cognitive science, since our linguistic capacities are a key aspect of human cognition. In this second meaning of the word “linguist”, many linguists are polyglots, but most polyglots are not linguists. I am this second kind of linguist.
More information about linguists and linguistics can be found here: https://www.linguisticsociety.org/what-linguistics. You can read about the lives of some professional linguists here: https://blog.linguistlist.org/tag/featured-linguist/. You can get a sense of how linguists think about language here: http://languagelog.ldc.upenn.edu/nll/.