There may be unwanted object (such as boxes, bushes), or a subject (a person), etc. in the scene which you may like to do away with so that your image just show what you intended to present. You may do this by using different techniques.
Here are the videos that may show you how to remove unwanted object step by step:
Using Clone stamp tool:
DavidPeterPLN. (2008). How to remove unwanted objects or people.