To Boil Something
To Simmer Something
transitive verb, ichidan verb
Because the hiragana ends with an う sound, you know this word is a verb.
The kanji itself means boil and the verb vocab version is to boil something. This is a transitive verb, so it's used when you put something into a pot and boil it up.
にる
The reading is the same as the one you learned with the kanji.
今日は、この脂ののった秋鮭を煮てみたいと思います。
We are going to simmer this fatty autumn salmon today.