This is the 10339th most frequent Russian word.
бумагу
"Бумагу" means "paper" (accusative case in Russian).
The word "бумагу" is in accusative case, indicating the direct object of the verb "взял" (took) and showing its purpose (for drawing).
Я взял бумагу для рисования.
I took paper for drawing.
The word "бумага" appears in the nominative case because it is the subject of the clause "мне нужна бумага" (I need paper), expressing necessity.
Чтобы написать письмо, мне нужна бумага.
To write a letter, I need paper.
The word "бумагу" in this sentence is in accusative case, being the direct object of the verb "использовала" (used) and indicating the medium used.