There are different ideas and logic systems in different languages. I don't know Vietnamese, but Asian language speakers in English can often seem a bit vague because they organise their ideas differently. In English writing, we aim to make clear concise points, generally one per paragraph. We state the point in the topic sentence, which is usually at the start so that the reader grasps the idea. then we develop the point. When that is finished, we start a new paragraph. Try making a list of points you want to make, then use that list as the basis for your pargarphs and that might make the writing easier for us to follow.
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