Resolution

 module Foo
   x = "I am in Foo"
   macro resulation()
       :(x)
  end
 end

 julia> Foo.@resulation()
 "I am in Foo"

 julia> macroexpand(:( Foo.@resulation() ))
 :(Foo.x)
 x = "current"

 module Foo
   x = 100
   macro resulation()
     esc(:(x))
   end

   res = @resulation()
 end

 julia> x = "current"
 "current"

 julia> Foo.res
 100

 julia> Foo.@resulation()
 "current"

 macroexpand(:( Foo.@resulation() ))
 :x

So a variable in macro, if it is not in esc, it will be resolved in where it is defined.
If it is in esc, it will be resolved where it is called.

Resolution for arguments

You can resolve an argument by $(esc(exp))
eg:

 module Foo
   x = 100
   macro foo(exp)
       :($(esc(exp)))
 end
 end

 Foo.@foo( x )
 "current"

and you can do this by esc(:($(exp))) too.

 module Foo
   x = 100
   macro foo(exp)
      esc(:($(exp)))
   end
 end

 julia> Foo.@foo( x )
 "current"