What kind of menu is recommended for mobile applications? What is the maximum number of items to place in the menu? Regards.
There's no concrete number to provide.
One somewhat relevant number here is the "magical number" 7 +- 2, which serves a rough estimate of how many items a person can generally hold in short-term memory.
However, it's not necessary to limit yourself to that number. Just know that not being able to keep all the items in short-term memory could potentially be annoying for users if it's useful for them to remember and potentially compare the available items. (Desktop example: if they're looking for the most fitting place to find "Options" and "File", "Edit," "Tools" and "Application" are all menu items.)
In general, the longer your menu is, though, the more exhausting it will be to go through. If your menu is long, something that will help users orient themselves more easily is grouping menu items into logical categories. That way, users can skip/ignore categories that aren't relevant for their current use case and only focus on the group that is relevant to them.
As for how to find out whether your menu is too long, I recommend conducting user testing for that.