When you add a budget file, you have three options for what to do with the data. For example, suppose the sales vale was $50,000. By default the data is not split, and the total data goes against the whole month. You might prefer to split the total value proportionately into the relevant days in the month.
Do not split - The data remains as it is; it is not split. Each month has its own value (measure).
Working days - Select from one of your custom working days calendars. The data is split by the number of working days in that calendar month and spread proportionality across each of the defined working days. Each of those days has the same value (measure).
Calendar days - The data is split proportionality across the number of days in the standard calendar, so each day has the same value (measure).