The macro language is used to refer to a SiteSupra object property from a block property.
A good example of the situation when you may need a macro command is adding a page title into the page text.
If you type the title into the text directly, you might need to update the text every time when the title is changed.
Using a macro command to insert the page title into the text makes SiteSupra to look over the changes and display correct page title.