Thanks.. english is a second language to me. I am not from d hoods.
mV = (Vin * 5000) >> 10;
That line of code multiplies the adc reading by 5000 and then divides it by 2^10. The result is the adc reading in millivolts. (more or less accurate. Not perfect conversion, but good enough for many)..
EDIT: Sorry.. I think I might have explained the wrong conversion .. sorry for that. I'm in a hurry.
I don't know what generated the spaces.. well, it is the "LongToStr" function, but I do not know why it generates leading spaces. That is a strange design.
The code probably loops from 0 to 11 because the char array "op[]" is 11 characters long. The code does not show how that variable is defined.
Edit: Ian explained why the function outputs the string "right justified". The code is out of context so it is impossible to explain it with more detail than that.