Checkpoints - Headings should be no longer than  words in length
Short headings make a web page easier to scan. Lengthy page headings and subheadings can be harder to read, especially if they wrap onto the next line. The shorter the heading the easier it is for trawlers to scan. As lengthy page headings and subheadings can be harder to read, especially if they wrapped onto the next line. Short headings that don't wrap improve readability, and promote effective online communication.
Now we know H1 tag is most important tag so whenever you going to use it for your webpage heading just try to make it like that people get an idea about your website just reading your heading. So that h1 tag should be in that way which describes everything about your web page just in one shot.
The purpose of this checkpoint is to look for the <h1> headings and make sure that it is within the 10 words limit, if it goes over this limit then this will be flagged as an error.