Okay kiddo, so "Bene Ephraim" refers to a group of people who live in India and believe that they are descendants of one of the 12 tribes of Israel, called Ephraim.
Long time ago, lots of Jewish people left Israel and traveled to different parts of the world. Some of them ended up in India, and over time they mixed with the local people and created a new community called the Bene Israel. The Bene Ephraim are a subgroup within the Bene Israel community who believe that they trace their ancestry specifically to the tribe of Ephraim.
So basically, Bene Ephraim are Jewish people who live in India and have an ancestor in their family tree from a certain tribe in Israel called Ephraim. They are a special part of the bigger Bene Israel community.