What does Revelation 8:6 mean?

This verse reports that the seven angels holding seven trumpets prepared to blow them. We do not know whether John saw this preparation in a sense as literal as witnessing the motion of angels raising the trumpets to their mouths. We do know, however, that preparation is always in order before we do God's will. Moses' preparation to lead the people of Israel through the Negev involved forty years of shepherding herds in that land. Joshua prepared to lead the Hebrews into the Promised Land, and was commanded to meditate upon and obey God's Word (Joshua 1:1–9). Jesus prepared for His work of redemption by praying (Matthew 26:30–46). The disciples prepared for the task of proclaiming the gospel in Jerusalem, in Judea and Samaria, and to the end of the earth (Acts 1:8) by praying (Acts 1:12–14). The apostle Paul prepared for the task of preaching the gospel by spending three years in the Arabian Desert (Galatians 1:11–24).

These upcoming judgments are part of an ever-increasing tide of trouble on earth, which is why this era is referred to as "the tribulation."