The Debug -> Macros tab is displayed only when macro debugging is enabled. This can be achieved either by configuring certain settings in Site Manager -> Settings -> System -> Debug, or by adding specific keys to the appSettings section of your project's web.config file. Both options are described in this context help topic.
On this tab, you can see which macros were recently resolved. For each macro, its exact expression, result (1 - resolved successfully, 0 - not resolved) and context from which it was called is logged. This is useful if you want to analyze how macros were processed.
Enabling the Show complete context check-box displays complete context (not only the topmost item) in the Context column. The log can be cleared using the Clear macro log button.
For more information about debugging in Kentico CMS, please refer to Developer's Guide -> Development -> Debugging and system information.