The PSU or most commonly known as the Power Supply.
Wait.....What do you mean?
You would want to add multiple text slides.
I hope this helps as the wording of the question was unclear.
from left to right because it is used more in expressions
Simple and easy user interface design can help the users understand what they can do on the website, without confusion when they are loading on the website.
Best practice on the users experiences can help the users to visit the website easily and get what they want as fast as possible. It is the way to improve a website understandability.