What is macros ?

Answer 1

Macros are the preprocessor definitions (literals).

#define EXAMPLE value

Answer 2

Here is how it works:

when u want print variable or macro that equals 1234

disassmebly:
with variable:
mov [ebp+var], 1234
mov esi, esp
mov eax, [ebp+var]
push eax
call printf
with macro:
push 1234
call printf