Jeremiah 29:11 expresses that God has a plan for his people that will end in a positive future. Some observers attempt to interpret the verse as a promise of individual prosperity for faithful Christians, while others use the context to offer a more general view of God's promise.
Jeremiah previously declared the divine prophecy that doomed the Israelites to exile in Babylon for 70 years. The Israelites viewed the prophecy as a hopeless proposition. As a result, they flocked to false prophets, including Hananiah, who prophesied that the exile would end in a shorter period of time. This situation led to Jeremiah's statement at verse 11 of chapter 29.
The first part of the verse, "I know the plans I have for you," emphasizes that God had a set idea of what was going to happen to the Israelites in the coming years. Because the plans were set, the Israelites were incorrect to believe that the time of exile would be shortened. However, the second part of the verse, which states that these plans were "for welfare and not for evil, to give you a future and a hope," is included to remind the Israelites that the prophecy of exile was not a death sentence. God hoped the Israelites would not lose sight of their pending liberation from Babylon.
Some modern-day Christians prefer to interpret the verse by itself as a promise that God intends to provide faithful servants with a bright future, even if it doesn't come as immediately as one would like. Other Christians take a long view and use the context to apply the message to an impending hope in the future for Christians as a group, rather than an individual promise.