The Instrumental Plural of Nouns

Творительный падеж имён существительных (мн.ч.)

1) The Instrumental case of a noun denotes the instrument or means by which the action is performed

and answers the question чем? (with what?)

Я рисую карандашами.

2) The Instrumental case of a noun with the preposition с may denote:

a) the person in conjunction with whom the action is performed and answers the question с кем? (with whom?).

Преподаватель занимается со студентами.

b) an attribute of an object, in which case it answers the question какой? (what (sort of)?), c чем? (with what?).

На столе стоит ваза с фруктами.