Traduction :Il y avait une orange dans la cuisine.
"Il y avait" is simply saying that an orange exists in the kitchen. It is a state of being. In English we call "was" a "being verb" because it just means that something is a certain way. All the being verbs are "am, is are, was, were, be, been, being." If you were to say "had," it suggests ownership. For instance, "I had an apple in the kitchen, but someone ate it." Vs, "An apple is in the kitchen"