.NET 4.7 provides built-in support for C# 7.0 features (like Tuples and Pattern Matching) out of the box. While you can hack these features into older frameworks via NuGet packages, having them native in 4.7 makes the codebase cleaner and the build process simpler.
If you are not a developer, you don't "use" .NET 4.7; you simply need it installed so other apps work. net framework 4.7