This report shows your average in words, lines, etc. (the units you defined) per hour, for every service you offer, per month and for the entire year. Good to know: this report only takes into account the jobs for which you tracked your time (and for which no time tracking is in progress) and which are defined as 'Finished' or 'Invoiced'. On mouse-over on a number, a tooltip tells you how many jobs were taken into account in the calculation and the total of words, lines, etc.
If you're using LSP.expert as a team (Team subscription), please note that if several users worked on the same job, their time for this job won't be taken into account in the Performance report.