Difficulty to understand how to support multiple screen

Question

I have seen so many questions on StackOverFlow how to support multiple screens. But most of the answers provide this link and this. And in the first one link I have

Answer 1

From Android: Supporting Multiple Screens

px = dp * (dpi / 160)

---

So for your example:

Your image dimensions are 960dp x 720dp and your dpi is 320 (which you can see falls under XHDPI).

Height = 960dp * (320 / 160) = 1920px

Width = 720dp * (320 / 160) = 1440px

Height and width are arbitrary depending on the orientation of the phone