A list is an ordered sequence written in braces. A table column is also a list: Raw[Amount] extracts the Amount values. List.Sum aggregates numbers, List.Select keeps matching items, and List.Transform changes each item. List.Distinct removes repeated values without turning the list into a table.
List functions work on values rather than rows. If you filter an extracted Amount list, the ID and Team columns are no longer attached to those amounts. Use Table.SelectRows when you need the original records. To return a scalar result in the editor's table preview, wrap it in #table with a named output column. Null is a missing value, so remove nulls deliberately before calculations whose denominator is a count. These exercises include repeated team names and a zero quantity to make those choices visible.