A request such as 'please explain' is a pretty generic inquiry. The best way to review a solution is to click on a particular step and then review the provided explanation.

Also, in order to see more steps of the solution go to 'Options', select 'Show: a lot of steps' and click 'Apply'

Please note that you cannot click on the very first expression, which is the original problem. Quite often, several transformations will be performed within the same step. Use the explanation navigation buttons to step through all of them: