It's a virtual language school hosted on Zoom. So you sign up, taking a placement test and then start learning with their curriculum. There are 10-12 thematic "chapters" in each level which correlates to a CEFR level and 4 "lessons" within each chapter: vocabulary, communication, grammar, and a review lesson. Those "lessons" are the classes and they build upon one another so that you learn relevant vocab, grammar, and pronunciation related to the chapter theme (say, "the grocery store" or "the train station" or "going to work.") There are 50-ish lessons total in each CEFR level. Each class has 4-5 students max but as I got more advanced my classes were more like 1-3 students.
Most people know of Lingoda because of their "sprints" where you commit to taking X classes in Y amount of time and get a massive refund. Of course, it's very hard to actually complete the sprint because the rules are intentionally very specific and you can't take more than one class a day as part of a sprint so if you fall behind it's impossible to catch up. They also have "marathons" where you get a (smaller) discount for attending 90% of your classes over a longer period of time, like 3/6 months. And then they run a subscription service where you pay monthly for a set amount of classes.
The most valuable part of Lingoda is that you have access to their whole curriculum from vocabulary lists to grammar explanations and they even offer pages upon pages of "homework" at the end of each lesson. However, I think most people who do the sprint are so busy attending classes they don't have time to take advantage of that stuff. Also, bc of availability it's nearly impossible to attend the classes in the right order all the time. Sometimes I'd have random beginners in my intermediate classes because they were in a sprint and just needed to attend *something* to get credit for the day. So that was a bit annoying for everyone involved.
TLDR It's definitely a legit company but runs with the classic DTC subscription model so you can't see pricing till you give them your info, can't purchase classes without a subscription, etc. I'd recommend the marathon (which I did) but not the sprint, it's set up for you to fail.