block (someone's) view
"Blocking someone's view" means putting something in the way and preventing a person from seeing something that they want to see.
For example, if you want to look out of your window and see your neighborhood, but there's a tree growing in front of the window, you can say that the tree is "blocking your view".
A person's view can be blocked by:
- a tree
- a car
- someone's body or part of their body