Provide equivalent alternatives to auditory and visual content. Provide content that, when presented to the user, conveys essentially the same function or purpose as auditory or visual content. This guideline is really very simple in purpose and execution. When composing documents, take steps to ensure they are clear and concise. If using graphics or sounds then make sure there is a text explanation of the graphic or sound being presented. Here are the main checkpoints of the guideline.
When designing a website implement this guideline by using alternate text with any pictures, and if playing any movies of any kind have an audio file option instead for visually impaired users. With the many non-visual tools technology have provided there should be plenty of options to put this into effect during website design. Another point that should be made is the use of simple language, don't flower up explanations or paragraphs. Keep in mind that mentally handicapped users want to understand the site as well. Following this and the other points will make this site accessible and stimulating for any and all users.