When the action performed by Ｎ1(i.e., the subject of the first sentence) is also performed by Ｎ2(i.e., the subject of the second sentence), Ｎ2 is marked by も(as well; too; also).
ジョンさんは ひらがなを かきます。マリアさんも ひらがなを かきます。
John writes hiragana. Maria, too, writes hiragana.
Lesson 1-7「それも がくせいの つくえです。」
That, too, is a student's desk.