Semantic headers are important for browsing pages with a screen reader.
Using semantic headers simply means using the h1 to h6 tags.
The header above looks like a header, but it is not a semantic header. As a result, it is not picked up by screen readers.
This is a semantic HTML list of the steps to use semantic HTML:
The wrong way to do this:
1. Use div tags and styling to mimick buttons
2. Use div tags and styling to mimick headers
3. Use div tags and styling to mimick lists