The filter dialog box shows the minimum and maximum values for the field below the range slider. These numbers give you context when you are deciding the range of values to include in the filter.
These minimum and maximum values are affected by the other filters set on the view. For example, a database may include records with sales ranging from $0 to $89K. If you created a filter on the Sales field the minimum and maximum values shown in the filter dialog box would indicate this range. However, let’s say you then filter the view to only show Office Supply products, which sell for between $0 and $25K. By default the filter dialog box will consider that filter and only show the office supplies range. You can use the Show menu in the bottom left corner of the dialog box to switch between Only Relevant Values and All Values in the Database. These options only affect the range that is shown in the filter dialog box and don't change how the filter will be applied to the view.