
A macro conversion is the main conversion on a website. Macro conversions are primary. Macro means big or on a large scale. Macro conversions show the conversion rate of a website which is quite important for a brand or a service.
For example, selling a product or receiving a service request are macro. Micro Conversions may often promote to macro conversions. That's why you should track micro conversations closely.
You can review the definition of conversion on wikipedia.
There are fewer macro conversions than micro conversions because macros mostly exist at the end of the sales funnel. If you get a macro conversion, this means that you successfully achieved your goal for that particular customer.
Conversion Rate Optimization (CRO): The Beginners Guide