I want to display those issue which are updated from last 15 days on the board

[Nic Brough -Adaptavist-]

Boards use filters to choose what issues to show.

You could have a board based on "updated > -15d", but then you'd be ignoring older issues, it's not something I'd generally recommend for a working board.  More of a reporting board.

If you're asking for this for an existing working board though, then add a quick-filter for "updated < -15d".  When active, that filter will hide issues that have not been updated for 15 days from the board.