Wipe, in a computing context, means  to render all data on a hard drive unreadable. The term is often used in reference to making data stored on a computer, smartphone or tablet inaccessible before disposing of the device.
A semantic HTML tag is one that defines a meaning to the enclosed content that a computer can be programmed to understand. In most cases, browsers create some visual difference to content in semantic tags, for example, content in the CODE element is usually displayed in a monospaced font. But this is not a requirement. Many people feel that semantic HTML elements are a waste of bandwidth.
Line 8: <p>For all good peopleâ¦</p>. This is another tag that you will recognize as semantic once you know HTML better. And it might be more obvious what it is in a longer page with more of them. This is a paragraph tag. It might have been more semantic if it was written <paragraph>. Line 9: </body>.