I don't quite "get" that line either, taken out of context. But I can tell you that everything in C# is an object, it's the most fundamental "type". This is roughly equivalent to the "variant" type in other languages. "Boxing" is similar to casting. Specifically, though, it is a way of treating value types as generic objects. A value type would be, for example, an integer. There are special cases where you might desire to have a value treated as an object, in my experience this has come up a time or two when doing COM Interop in C#.

So I think what's being said is "Delphi Variant types are roughly equivalent to Objects in C#".