This section appears for post queries and it is helpful to restrict your query using dates. See WP Documentation.

• Date After/Before:  Activate this option to enter values for after and/or before dates, to set a custom interval from where you will want to get posts.
• Year: Enter a four-digit year number.
• Month: Enter month number 1-12.
• Week: Enter week number 0-53.
• Day: Enter day number 1-31.
• Hour: Enter hour number 0-23.