Agile is a methodology or culture of iteration and rapid learning. It aims to de-risk projects by avoiding very long periods of development without any validation that it is actually working, or solving a problem for a client/customer. Hence delivering smaller milestones and iterating towards a final product, not planning one massive milestone and spending months working on it... before showing it to a customer.
However that's just my take on Agile and many purists would disagree ;)
A big problem is that many "agile" workplaces just have non-age processes with Agile ceremonies sprinkled over the top - "Waterfall With A Standup". Or, they have sprint planning and a backlog but absolutely no higher-level strategy or goals - "Making It Up As We Go Along". Which isn't really getting any value out of Agile.
It sounds like the real problem is you didn't get any real onboarding or instruction on how your company does things... If you have any scrum masters around maybe ask if you can buy them lunch and get them to explain how it's all meant to work. You may find it's not really embedded yet, but they'll probably be happy you're interested :)
Or perhaps it would help to go along to an agile meetup and talk to people who are keen on it (not sure if Agile Vietnam still hold a regular meetup in Ho Chi Minh, they just did a conference though agilevietnam.org).