The two boxes on top of the report will show you the result across all your sources by two different spend scenarios:
On the left-hand side, you can see the results of your last 30 days media spend history.
On the right-hand side, you can see the (optimized) results which would have been possible to achieve if you’d have spent your historic budget based on the SPHERE recommended scenario.
In this particular case shown in the screenshot above, you could have increased the number of conversions without increasing the amount of budget spent if you would have spent your budget as SPHERE recommended it. Hence SPHERE would have spent your budget more efficiently as it was the case in the past.
As this is only an overview on top-level across all sources, you can find a more detailed scenario comparison of spend and outcome (conversion) on the bottom table.
There you can see exactly - source by source - how you did spend your budget in the last 30 days and how SPHERE would have recommended spending it. This report table can be used to rethink your budget allocation for the upcoming period. Or you can verify that your historic budget allocation was almost as good as it gets.