You sit in a chair or lay down on a table (my preference) and someone who does this all day long, puts a bright light near your ear and uses a razor to cut off the hair on the outsides of your ears (if you have any) and then uses a bunch of different tools [0] to extract out all the ear wax and anything else in there. I always come out feeling like my hearing is more 'clear'.
They literally touch your eardrum and the feeling is somewhere on the edge of uncomfortable, but oh so good at the same time. At the end, they use a very fuzzy q-tip and it makes this wonderful noise and feeling.
Of course, I've heard horror stories about this not going well. Punctured eardrums, infections, etc... but the fact is that literally millions of people every day get this service in Vietnam. You see people all over getting it in shops. You also learn quickly that if you don't like something, move your head away and they stop immediately.
If you get this often enough, you should purchase your own set of 'tools' (about $4-6) that you carry with you and have them sanitize them each time before use. I went to a whole bunch of different people and eventually found a few places that I liked a lot. For the most part the service is the same all over, but everyone has their own unique different technique too.
[0] https://chamsoccothe.com/uploads/images/san-pham/lay-ray-tai...