Wordpess.org site menu options spacing

I'm using Wordpress.org to create my website. Also, I have used a theme that is already available.

Now my issue is on adding the menu items, in the sub-menu category with 6 items, only for one menu item, there is a space between it and the next menu item. I'm not able to remove the extra space.

I have not used any CSS code to design my website. I need to remove the extra space as it appears as if there is a hidden menu item between the two items, so how can I do that? And what could be the reason for the extra space for one particular item only?