A performance target forecasts campaign group performance so you know whether you’re on track to meet specific numeric goals. If it looks like you're not on track, you can consider adjusting your campaign’s settings to improve performance.

• A performance target is measured by specific metrics related to clicks or conversions for a single campaign group.
• A single campaign group cannot have multiple performance targets with overlapping date ranges.
• Performance targets are only available for campaign groups (not single campaigns).
• Set a performance target when creating a campaign group or in the "Performance targets" tab of an existing campaign group.

* Nguồn: Google