NEW with API

Hi, I am trying to learn API. And I am so new with it, therefore I don't know how to make a API calls for now. I know that I want is to get some data with this link Tỷ giá USD/VND hôm nay 01-12-2024, so sánh tỷ giá ĐÔ LA MỸ tại các ngân hàng, gia USD. But I don't know how does API work in ninox, can some one help me please. 

 I just want a simple number field overthere. Please help. Thanks you so much.