Subject
noun, の adjective
The main thing you talk about in your language becomes the subject of the sentence.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
主語が大きい
large subject matter
主語が分かる
to know the subject
主語がある
something has a subject
この文の主語は何ですか？
What is the subject of this sentence?
先週の日本語のクラスで、主語の使い方を学びました。
I learned how to use subjects in Japanese class last week.
日本語では、いちいち主語を言わなくても相手に分かってもらえる事が多いんですよね。
In Japanese, even if you don't say the subject every time, the listener would often get it.