Hot Thing
Hot
い adjective
This is for when a thing is hot, making this word hot thing. When the weather is hot that's 暑い. This is when you touch something and you burn yourself.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: This has the same reading as 暑い, so if you've learned that you'll know how to read this word as well. If you haven't run into that word, you've probably run into the kanji 暑 at least. That uses the reading あつ. Two similar concepts, but there are two kanji to differentiate, which gets confusing.
私は熱いお茶が好きです。
I like hot tea.
でも、これはちょっと熱すぎます。
But this is a little too hot.
うちらの高２の時の先生、すごい熱い先生だったよね。
Our teacher back in our second year of high school was really passionate, wasn't he?