How to get latest post date in category page?

[mmistakes]

You can directly access the first and last post objects this way, eliminating the need for the for loop. See this thread for more info:

Question about site.posts values

Oh and even simpler are first and last. Use dot notation and you can access the entire object. In your case {{ site.posts.first.title }} and {{ site.posts.last.title }} will get the title of the first and last posts. You can replace title with any variable available in the post’s YAML Front Matter… date, content, excerpt, etc.