What's your focus in this picture? Of course, it's the red word "focus". We see the other words though they are blurry and stretched.
In our writing we need our words to work together so they are coherent and help the reader to focus on the subject we're writing about. Our sentences must work together to help us keep the subject we write about front and center in our readers' minds.
I think that's why writing fiction can be difficult. The writer has to keep the reader focused on many things: the main character, plot, and theme.AND the writer has to blend them all together so the reader becomes wrapped up in the story and doesn't even think about the words because they are desperate to find out what happens next.
What author do you think does a great job of keeping readers focused on the story? This might help you think of one, what was the last book you read that you could not put down?