Instantiate
In short: Instantiating means creating a concrete object (an instance) from a class.
In more detail: In Java this is done with new and a constructor.
In Depth
Dog bello = new Dog("Bello"); // instance of the class DogThe class is the blueprint, the instance the house. The memory for the object lies on the heap, the variable bello holds the reference to it. See classes, initialise, garbage collector.
See also: Klassen, Initialise, Garbage Collector