When was Israel formed?
Assuming that you are talking about the modern state of Israel, this country was created in May of 1948.
Israel was created soon after the end of World War II. These events are very closely connected since it was WWII that really led to the creation of Israel. During WWII, of course, millions of Jews were killed in the Holocaust. For this reason, many people (Jews and others) felt that Jews needed a country for themselves. On May 14, 1948, the United Nations approved the creation of the new country of Israel to serve as a homeland for Jews.