Has outgoing hreflang annotation to multiple URLs
This means that the URL in question has hreflang annotations that specify the same hreflang to multiple different URLs - so there is a conflict between the various annotations.
Why is this important?
Hreflang tags are interpreted by search engines as indexing instructions. An English page that has hreflang pointing at its French alternate is instructing search engines to index both the English version and the French version, and to consider each as equivalent in their respective languages.
In this situation, we describe the English page as having outgoing hreflang to the French page. If the English page were to list the French URL as fr-fr (French-France), but also list the Spanish URL as fr-fr (French-France), this would case a conflict.
How would search engines know which page should be considered the French alternate?
This sort of conflicting signal will cause search engines to ignore the hreflang instruction.
What does the Hint check?
This Hint will trigger for any URL which has multiple outgoing hreflang annotations, where the hreflang is the same but the URLs are different.
Note: This Hint is very similar to another Hint: Has conflicting incoming hreflang annotations. The difference being that this Hint is analysing the page with hreflang on (i.e. outgoing hreflang) whereas the other Hint is analysing the target page of a hreflang annotationn (i.e. incoming hreflang).
Examples that trigger this Hint:
Consider the URL: https://example.com/en/page-a/
The Hint would trigger for this URL if it had conflicting outgoing hreflang;
How do you resolve this issue?
The first issue is that the same hreflang is being referenced multiple times - each hreflang should only be included once. The second issue is that the hreflang conflicts.
The problem with this sort of conflicting instruction is that it is not obvious to search engines which annotation is correct and which is wrong. Hopefully, it is easier to figure out as a human (with some knowledge or awareness of foreign languages!).
You will need to inspect the hreflang to identify the incorrect pattern, then either manually update the URLs to correct the mistake, or fix the script that generates the hreflang (depending on how the site is setup).
Ultimately, you need to end up in a situation where there is only one (correct) hreflang annotation for each hreflang URL.