In imperative programming, the programmer is responsible for writing how a program should execute. Imperative programming uses statements to direct the program in a sequential manner. For example, when iterating through a list you might write a statement like index += 1 to both increment and set an index variable.
We use the term "imperative programming" to describe a programming paradigm. It's a fuzzy description which is applied to languages but is often a matter of style and of what language constructs a programming language provides.