Informative Pop Up

Hi, I would like to know if somebody can help me to expand an icon, like clicking on a text and opening a window with more information about it, without having to create another page.

I would like to put this functionality on this section:

When people click on Coaching, Workshops, etc, it may open a window with further information, but still on the website one page.

Let me explain better with an example. On the website http://www.clubedopost.com.br when you click on the menu “SERVIÇOS” (means services in portuguese) it will show all the services of this company. when you click on some of the services it opens like a giant pop up explaining the service.

Maybe a plugin or any configuration on the theme could fix it.

Thanks a lot!

Cheers
Caio