The low text-to-HTML ratio means that you have more code in the page source than the original human human-readable text.
For example, you are reading this text in English here which is referred to as text while when you go to the view source of this page you would find plenty of technical code which is normally called HTML
What is the Benefit of Fixing it?
Faster page speed: More code generally takes more time to render which can make the page loading time slower. A faster site is probably going to load quicker for users and can rank higher in search engines.
Better Content: Good quality content doesn’t need to be long however if it is too thin then it may not make sense to the reader. So tools like SEMrush reports low-text-to-HTML as a warning so we can check if the content is too thin and need improvement.
How to Fix Low text to HTML issue
Increase the text and number of words if needed: You can increase the word count on your page however it is not something that is required. For example, a contact page may not be needed to look like a blog page so in that case this would be fine.
Reduce the code: Double-check the code because sometimes we can optimize the code. Removing inline style and script code and hosting to separate files can help reduce the code without removing any feature.
In general, we don’t need to worry about a low-text-to-HTML ratio because it is not what Google looks for however as good quality sites have so many good things in them. So it is better to tap into every opportunity available to improve site quality.
Here is a reference video by Google search advocate John Mueller on low-text-to-HTML term.
SEO Expert. Digital Marketer. Website Developer and Owner at SalamExperts