Code Hints suggest the best guess from editor. Suggestion takes into account existing code templates, auto correction data, keywords from dictionary and statistical data collected by editor from exsisting text and when your type new text.
The best guess calculation is syntax and context dependent.
You can accept the suggestion by Tab or Enter and editor will complete the rest of the word/template for you.
If you type a code template key, HippoEDIT will show you the Code Template description and will enter the text if you accept the hint.
The inverse tooltip indicates that editor has more than one suggestion.
You can enable/disable the feature in Options->Code Completion.