Language teaching has swung through some pretty large swings over the last hundred years.
First off, there's approaches to language learning without any coherent methodology and there are also misapplications of methods for purposes for which they were not intended.
As mentioned in another answer, there's an approach now called grammar translation. The idea is that you learn the grammar of the language and with a dictionary are then capable of translating primarily written materials into your language. GT is primarily suited to reading ancient languages where the value of production is minimal and the point is to be able to decipher the text precisely.
This was supplanted by the audio lingual method. Here, you're going to be hearing and seeing a lot of things in the language and speaking, and you will be required to produce in that language.
A further method is the "Berlitz method" or others like it which are all about immersion.
More recently, there's also TBLT (Task-based language teaching), which is based on functional and situational use of language. There's also PPP (presentation, practice production), which says the instructor should demonstrate, then students practice, then students produce novel items.
That's a lot of words. tldr: there are lots of theoretic approaches to language teaching. On a practical level, the differences are often (but not always) small. The proliferation of these methods is motivated by theoretical considerations about the nature of language learning. The reality is that language learning takes time and each method has advantages and disadvantages with respect to different goals. (E.g., I don't care if I can't say a single sentence in Latin (or for that matter Danish) since my goals are reading philosophical texts, but I care greatly if my Japanese is conversant and whether I can produce comprehensible e-mails and hopefully academic papers).
I would doubt you had a pure GT approach in your high school. I would guess there some eclecticism in the teaching method used at your school.
For instance, here in Japan, grammar translation (common but officially not allowed) is a crutch for instructors who themselves do not speak English to have something to say to their students where their knowledge is superior.
If you want to read me Wikipedia has several good entries on language teaching/learning methods (https://en.wikipedia.org/wiki/Language_pedagogy)