Hi,
I can see that you this is the Nop Electronics Theme v 2.5. The empty space you can see is because there is a predefined place for a banner on the left side and when it is missing there is an empty space left. In order to fix this you can either add a banner following the Nop Electronics
online documentation and more precisely point
18 where you will create a banner with an exact system name "LeftSideBanner" or
you can edit the ~\Themes\Electronics\Views\Shared\_ColumnsThree.cshtml and edit the following lines as shown below:
<div class="block"> @Html.Action("Slider", "AnywhereSliders", new { systemName = "LeftSideBanner" })
</div>remove the first and the third line in bold.
This situation has been fixed in version 2.6 of the Nop Electronics Theme.
Thanks!