When a visualization has a date/date-time axis, you can drill in different time levels (year, month, date, hour, minute...).
For example, a user views sales amount broken down by year could drill down to see the same metric broken down by quarter/month/day/...
Simply right-click on the chart → select a period → the chart will show the values aggregated up to that time period.
Date Drill only affects the result set of your SQL report
Date Drill does not alter the SQL of your report - it only performs aggregations on the resulted data. Do take care when you work with averages or ratios to avoid incompatible drillings.
For example, your original result set contains Daily average order value (AOV). Using Date drill to aggregate it to Monthly level may not make sense as you will take average of averages.