A macro is like a little sequence of events which you prerecord and then the console, software, etc executes it.
For example, the Strand 300 requires 4 or 5 key presses to shut it down. I have a macro I recorded and assigned to one of the extra buttons that does these five key presses for me. Rather than press five buttons everytime, I press the button I asscoted with teh macro, and the board runs the steps I recorded.
Does your console support them? Look in the manual for macros, they'll be there if the console can do it.
Macros can also be recorded to run cues, start subs, or anything else you can do by manually pushing buttons. They can be a real time saver if you have a good reason to use them but I fiqure other than normal things like shutting of the board, it is easier just to program cues to do all of it. One thing they can do that's kind of nice is change system settings. Program it to switch different options and stuff like that and they can be pretty usefull.