What does this mean?

Heading elements (<h1>, <h2>, ...) must contain some machine-readable text content.

Heading should never be empty, or just contain whitespace:

<h1>   </h1>

Headings which contain images or other media must specify alternative text:

    <img src="heading.png" alt="Press releases"> 

See Technique H42 for more details.

99.1% done

How close this website is to fixing this issue.

HTML Found on page Issues
<h3 class="govuk-heading-m">&nbsp;</h3> 3
3 distinct issues were found in the sample of 113 web pages.
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