Persuasion, Convince
noun, verbal noun
You acquire theory after theory. In doing this, you have a lot of theories in your head. You use all these theories as tools for persuasion. These theories will allow you to convince anyone of anything.
せっとく
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. The 説 gets shortened to せっ.
彼女は上司を説得するためにプレゼンをしました。
She made a presentation to persuade her boss.
彼女はパーティーに行かせてもらえるよう親を説得しました。
She tried to convince her parents to let her go to the party.
彼の言葉にはいつも説得力があります。
His words always carry persuasive power.