Rhetoric
noun
The mastering words field of study is also known as rhetoric.
修辞学 is specifically for the study and theory of rhetoric. Rhetoric as an academic field, in other words. If you're just talking about the way people persuade each other with words, the more colloquial term is レトリック.
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.
修辞学のレポートの締め切りはいつですか？
When is the deadline for handing in the rhetoric essay?
この修辞学の本は、面白い上に有益です。
This rhetoric book is not only interesting but also useful.
私は修辞学の先生に恋をしています。
I have a crush on my rhetoric teacher.