The Operational Timings Outliers to exclude filter leaves out timings that look wrong, so they don't distort your figures. It is one of the header filters, so it applies to all the data of the dashboard.
The three options
No exclusion: every timing is kept. This is the default.
Impossible values only: leaves out timings that cannot be real.
Extreme and impossible values: leaves out extreme timings as well.
When should I use it?
Use it when a few wrong entries distort your averages, for example an average delay that looks unrealistic. To find where wrong entries come from, the AGOA Usage dashboard shows outlier values.