Each of the personal pronouns (except the 3rd plur.) exists in a longer and a shorter form: the one is used as a nominative and is a separate word, the other is attached to verbs and (in a slightly different form) to nouns to express the accusative or genitive.
With nouns, and of the final u of the third pers.
She makes many mistakes, of course, twists words and phrases, puts the cart before the horse, and gets herself into hopeless tangles of nouns and verbs; but so does the hearing child.
Many words are used indiscriminately as nouns, adjectives or verbs, without any change of form.
On March 31st I found that Helen knew eighteen nouns and three verbs.