Only has desktop organic search traffic
This means that the URL in question only received organic search traffic from desktop devices, per the connected Google Search Console account.
Why is this important?
This should be considered a flag - why did the page receive visits on desktop devices, but not tablet or mobile devices? It could signal an issue with search performance for the page on mobile and tablet devices.
What does the Hint check?
This Hint will trigger for any internal URL which recorded some desktop clicks from organic search (i.e. > 0), but no mobile or tablet clicks.
This data was collected from Google Search Console, via API, for the connected Property, and for the specified date range.
Why is this Hint marked 'Potential Issue'?
This Hint is a 'Potential Issue', which means that it is unlikely to be affecting the site at the moment, but should be investigated as it could cause issues in the future.
For example, there may exist a separate mobile site which serves mobile and tablet visitors (e.g. m.example.com), so you would actually expect the desktop site to only receive desktop traffic. If this is the case, you would simply ignore this Hint.
Similarly, it might simply be the case that there were only a few visits registered during the given time frame, and they just happen to be on desktop.
However, this Hint will also help you pick out instances where the mobile or tablet versions of the page are underperforming, which may actually be indicative of a much wider issue.