If you can't see it, we can't see it. I know sometimes we can get all excited about the scene we have figured out or the wicked dialogue we have planned, but we have to make sure we ground our reader. We have to show them where they are. What it looks like. We need to paint a picture but do it quickly. Readers now a days don't want to read three pages about the setting but they still want to know what it looks like and where they are. If you don't know what your setting really looks like for that scene, take a moment to close your eyes and see it. We won't need all the details you see but find the most important ones to give us what we need.
For example: If you are writing a scene that takes place in an apartment. What makes that apartment unique? Is it really clean, a pig sty, is it fancy full of modern furniture, or is it full of weird looking glass bottles. It could be a pretty regular apartment but we need to know that too, but then we'd want to know is it big or small? Is there something that stands out about it to help us imagine what you are imagining. If you see a dirty green couch next to a high end glass table, we need to see it too. These details tell us about the character who lives there and gives us a sense of place. We can then properly visualize where they are and what that might mean for the story.