The fields CREATED_DT and MODIFIED_DT in the audience list are automatically updated when a new record is created or modified resp. The Attribute tab is used to create the constraint based on profile attributes.
For datetime fields you can select before/after/between/not between a fixed point(s) in time, or sliding point(s) in time. If you select, like in this example, after a fixed point your selection would grow as time progresses. With sliding point, you use a time window, in this case of one week. Because "Now-1 week" will move along in time, it will always be "Now-1 week".
The operator is "> after" that point in time (-1week). Although verbally we say "less than" a week ago, mathematically it is "bigger than" that point in time. This selection is the same as "between now-1week and now". For between and not between you select two points in time. If you have problems making time selections, you can check the time line graph to get an indication what is in the selection.
There are some considerations when selecting ranges and times. For instance, "between 10 and 20" selects faster than ">=10 AND <=20". Using sliding points is slower than fixed dates. See tips on using the Filter Designer to create effective SQL constraints.
