Is this achieved with a plug-in or a template

I really like this website and I am not sure if they achieve the effects are like with the template or if it’s a plug-in. The website is https://WWW.SGNL.COM.

When I design my website I would like to have a similar gallery on my homepage. I like how they have the thumbnails with the rollover effects. I also like how when you click on one of the galleries like Print, you go to the image with a description on the side and you are able to click the next/previous buttons to go through the whole gallery.

If anyone could tell me where I can learn about how achieve the same outcome I would greatly appreciate it.