Labview won't tell you exactly the # of lines of code, it will give you a the total Code size (memory in bytes) - check the Help under Metrics. We use this value as a certain ratio equivalent to tradional lines of code for estimating projects. With a little guess work, and depending on what traditional text-based language you compare to, you might find that Labview code is a 1:2 or 1:3, ?? ratio.
I have my own ratios for comparing to C or C++, etc., and continue to fine-tune these differences. Think how 100 lines of comments in a tradional code skews estimates...