Final answer:
The sentence 'We play games with balls' indicates the ball's function.
Step-by-step explanation:
The sentence 'We play games with balls' indicates the ball's function.
Form versus function is an important concept in grammar.
Form refers to the way a word looks or sounds, while function refers to how a word is used in a sentence.
In this sentence, the word 'balls' is functioning as the object of the preposition 'with', showing what we play games with.
Therefore, 'function' is the correct answer.