Run Time in Sigma


I wanted to know more about the run time in query history.
As can be seen below, the run time shows 30.3/30.2 m. Does m stand for milisecs here?
Also can you please explain what this run time is for.

And if we click one of the queries, as below, the time taken is much more than the run time shown above. As can be seen it is 18 secs.

So can you please explain what time should we take to record the performance.