This is a core concept
Respondent funnel shows you the number and percentage of respondents who have clicked, segmented, subsegmented (if applicable) and converted in the campaign. The respondent funnel can be found within the Performance tab of all portfolios, campaigns, creatives and traffic sources.
The below screenshot comes from a specific campaign's respondent funnel. In this example, 4,850 total respondents have viewed this campaign over the last 30 days. 220 respondents have "segmented," meaning they clicked a tagged action. 27 respondents "subsegmented," or clicked a second tagged action. 154 respondents in this campaign converted within the last 30 days.