Shell, Shellfish, Clam
noun
The kanji and the word are exactly the same. That means they share meanings as well.
かい
The reading for this word is the same as the one you learned with the kanji, meaning you should be able to read this already.
川には、たくさん貝がいる。
There are many shellfish in the river.
貝のパスタとシイタケのパスタ、どっちがいいかな？
Shellfish pasta or shiitake mushroom pasta, which one should I get?
赤い貝のダシでつくったラーメンです。
It's ramen made with red shellfish dashi.