Great question — answering as the UphillTech team:
I'm gonna attempt to go simple as the OP requests. Each webpage with a title and meta description will contain source code with these lines in it near the beginning of the code: <title>insert title here</title> <meta name="description" content="insert description here"> ...Except that "insert title here" is meant to be the actual title and "insert description here" is meant to be the actual description. What google is telling you is that these two values need to be different for every page on your website. You can't use the same title on two pages nor can you use the same description on two pages. If by chance you're doing a site involving multiple pages that people can look through, then...
Full answer by Mike -- No longer here: https://webmasters.stackexchange.com/a/81219 (CC BY-SA 3.0).
Need it done for your business? UphillTech.