What actually is a restore?

Hi there!
Unfortunately by mistake, I have clicked the “reset to default” option on my theme and I have lost content on my homepage. Rest of the content for navigation, blog posts, contact form are intact.

I have a backup made just 2 days ago!

I want to know what exactly does the “restore” does. Will it bring the theme and its contents to the last backup? Please help. I appreciate.

Thanks