While knowing the exact meaning of “this generation” has eluded scholars for two-thousand years, what is clear is that Jesus will return and set everything right by judging wickedness and rescuing His people.
Because Jesus does not specify what “this generation” means when He said “This generation will not pass,” we can’t be certain. At least four views exist about what Jesus meant by this phrase, though it is most likely that He was talking about the last generation—those who see the signs leading up to Jesus’ return. If that view is correct, then His point would then be that the great tribulation (Matthew 24:21) will be short lived. Thus, the generation that enters that tribulation is assured that they will also get out of it. This is likely the interpretation because we are told in both Daniel and Revelation that the final days will be only seven years (c.f., Daniel 9:24–27 and Revelation 11:2–3, 12:6, and 13:5). Therefore, Jesus is providing comfort and hope to believers, not just to look for when He returns, but to know that, when the horror of that time starts, He is coming quickly!
We can focus so much on understanding prophecy that we lose sight of its significance. In Matthew 24, Jesus is talking about His return to judge the nations and establish His earthly reign. That will be a terrible time for unbelievers, with everyone from kings to slaves begging the mountains to crush them to get away from God’s judging wrath (Revelation 6:15-17).
While it will be a horrific time for His enemies, Jesus meant this passage for comfort. He gave us these signs so that we would have hope, would obey Him, and would share the Gospel.
Jesus gave us hope of relief (2 Thessalonians 1:7) by showing us that He is returning to judge the wicked in full (Revelation 20:11-15). Jesus knows what everyone is doing (c.f., Revelation 2:2, 9, 13, 19; 3:8) and will set everything right.
Jesus also told us this so that we would obey Him (John 14:15, 21) because even believers will be judged! While we will not be judged regarding salvation (we are saved by Jesus’ works), it’s a time where we must give an account of ourselves (2 Corinthians 5:10; Romans 14:10-12). By looking to His return, we grow in purity and become more and more like Him (1 John 3:2=3).
Finally, Jesus showed us these fearful things so that we would desire others to repent of their sin before it is too late. Jesus died as a propitiation—a sacrifice that turns away the wrath of God. Everyone who truly repents, turning away from sin and confessing Jesus as Lord, will be saved (Romans 10:8-13), which is a salvation from God’s coming wrath (Romans 5:9) when Jesus comes in the clouds (Matthew 24:30)!