1 The LORD spoke to Moses, saying,
2 "Send men to spy out the land of Canaan, which I am giving to the people of Israel. From each tribe of their fathers you shall send a man, every one a chief among them."
The book of Numbers tells the events of Israel as they fail to achieve their entry into the promised land (due to unbelief in the power of God to enable them to conquer the land). They are condemned to wander in the desert for many years until all of the unbelieving generation which left Egypt has died.
The book is called "Numbers" because of the census numbers recorded - the statistics of the people and nation.
Here, the record of events continues as Moses tells the people that God wishes them to spy out the land they are moving into, to get some idea of what they are facing and what to expect. Top leaders from each tribe are sent, which makes the failure on their return so much sadder. These top leaders, except for two, do not believe that God can overcome the inhabitants of the land. This unbelief is typical of the people (since this is the attitude which their chiefs have) and is what condemns them to die in the wilderness rather than find peace in the promised land.