Thank you for the opportunity to help you with your question!
Always remember that the square root function starts at the origin and curves up and to the right. So the square root function looks like this:
When you have a an (x - 4) inside the square root function, that means you are moving the graph 4 units to the right (right when it's negative, and left when it's positive, just remember that left and right are opposite in sign as to the positive and negative side of the x-axis. So the graph of sqrt(x - 4) looks like this:
If the - 4 is outside of the function, meaning, you have sqrt(x) - 4, that is a vertical shift, and the graph will move down 4 units, like this:
Please let me know if you need any clarification. I'm always happy to answer your questions.