Imperative code is procedural: do this, then this, then that, then the other, in that order. It's very precise and specific in what you want. Most languages that we use for building end-user applications are imperative languages, including VB.Net. Language structures that indicate an imperative language include if blocks, loops, and variable assignments.
Declarative code just describes the result you want the system to provide, but can leave some actual implementation details up to the system. The canonical example of a declarative language is SQL (though it has some imperative features as well). You could also consider document markup languages to be declarative. Language structures that indicate a declarative language include set-based operations and markup templates.
Here's the trick: while VB.Net would traditionally be considered imperative, as of the introduction of LINQ back in 2008, VB.Net also has significant declarative features that a smart programmer will take advantage of. These features allow you to write VB.Net code that looks a lot like SQL.
