Imagine you are having a conversation with someone and this is what they tell you:
Over the weekend me and my girlfriend went to the Mall. It was fun. I wonder what the new movies are on Netflix. I'm thinking about getting a dog. My birthday is next week. I can't wait for my vacation to begin so I can have my birthday party and see a new movie.
This paragraph is difficult to read. What is it the person talking about? The Mall? The movie? Their birthday? There is no specific train of thought. When writing you should stick to a particular focus/subject and elaborate on that topic until you want to transition into another topic.
This person would be considered GARRULOUS: excessively talkative about trivial matters.