There are several ways to become multilingual, for example, the acquisition of language or two languages is something that starts at home and refers to the first language or languages we learn, and acquiring a language ends when we reach puberty, according to multiple studies such as: Critical period hypothesis (CPH) claims that there is an optimal period for language acquisition, ending at puberty. . And then there is what we call learning a language, which is about learning a second language during or after puberty.
Clarifying this distinction between "language acquisition" and "language learning" let me show you my case. I belong to the second group, since I learned (and I am still learning) a second language after childhood (English), which puts me at a great disadvantage compared to most of my classmates, who belong to the first group or have considerably more years learning a second language than me. I can honestly say that I started learning English when I was 18 because although I took English classes in elementary school and high school I only learned (or memorized) what was necessary to pass the subject. I can not say that I learned English during those courses.
It was not until I decided my career (translation) that I worked hard to learn correctly what in the past I did not learn, because my future depends on how well I learn English. At first when I was already in my area of Language Sciences it was very difficult because I only had very basic knowledge of