To Boil
To Simmer
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.
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.