What is gross and net in the perf. report?

I did a trace by using ST12 and below is the report, pls. let us know

1) Actually, we want to know which step / program / piece of code / syntax / module is taking long time so pls. let us know which column we need to focus among Gross, Net, Gross (%), Net (%), in other words which column tells the time consumption?

2) What is here Gross, Net, Gross (%), Net (%)

3) What is the ' = ' here bcz for some records I saw ' = ' value

In the below report, I guess, the DURATION / 2nd column will tell us that each ABAP code line time consumption, am I right? So, which ever record  have more value in the DURATION column means that row's ABAP code is taking long time, right?

Thank you