In Japanese grammar, "主語" (shugo) refers to the subject of a sentence. It indicates who or what is performing the action or being described. For example, in the sentence "彼は走る" (Kare wa hashiru), meaning "He runs," the word "彼" (kare) is the subject. The subject can be explicit or implied in Japanese sentences. Often, the subject is omitted when it is clear from context. For instance, in the sentence "行きます" (Ikimasu), meaning "I will go," the subject "私" (watashi) is understood even though it is not stated.