Shopping
noun, の adjective
You've hopefully seen 買う by now and know it means "to buy." So, 買い is going to be similar to that. Add that to thing and you have a "buying things" sort of word. What does "buying things" describe? It describes shopping.
The readings are the kun'yomi, which is usually the case when there's hiragana in the middle. You learned the reading for 買い when you learned the kanji, as well as the word 買う, and you learned this reading of 物 in the word 物!
スーパーで買い物をしたばかりです。
I've just done the grocery shopping.
たまにはデパートに買い物に行こうよ。
Let's go shopping at a department store sometime.
今日はクリスマスの買い物に行くの！すごくワクワクするわ！
We’re going Christmas shopping today! I’m so excited!