What is the biblical definition of the last days?
The last days, biblically, cover the entire period from Christ's first advent to the end of the age. They are not limited to the Tribulation and Second Coming, which are called the latter days. In these last days God has spoken to us by His Son.
Les teaches from Hebrews 1 that the last days are not merely the Tribulation and Second Coming. He defines them as everything from Christ's first advent onward—the whole period from His first advent to the end of the age. The same triune God who spoke in times past to Israel's fathers by the prophets has in these last days spoken by His Son.