You can use filters to identify and isolate data based on some specific attribute.
Here's an example question:
How many of our customers are over the age of 25?
To answer it, let's assume we have a nice 'ole customer table that contains this information, like so:
To find and isolate customers over the age of 25, we would simply:
Click the header of the Age column.
Select Filter by Age, from the 3 options (Filter, Sort, Count) that appear.
Add our filter i.e. > 25.
Click save and Trevor will run the query and limit the results to customers who are older than 25. Done. Weehoo!
Depending on the type of data you're looking at, you can create different types of filters. For example, if you were looking at the Sales table and it contained the date on which each sale was made, you could create a filter to look at sales between two different dates (e.g. between the 1st March and 1st April), or on a rolling basis (e.g. within the last 7 days). If it contained the country in which each sale was made, you could create a filter to include, or exclude, specific countries.