Computer says no means that a computer has been programmed to give an answer of "no" to a specific request. For example, when you try to access a website or a certain file from your computer, it might say “no”. This is because the computer has restrictions or rules set up by the person (or thing) who controls it that tell the computer what to do. These rules are called “programs” or “software” and they tell the computer what is allowed and what is not allowed. So if your request doesn’t follow the rules, the computer will say “no.”