But it’s more than that, the context is more than that
The entire book of Jeremiah is a condemnation of the Jewish people and their disobedience before God. By the time we get to chapter 29 many of the Jewish people have been exiled to Babylon. Jeremiah writes a letter to them instructing them to stay put, to build houses, have sons and daughters and to pray for the city. To make themselves comfortable. V 10 says they will be there for 70 years!
The context of Jeremiah 29:11 is the Jewish people rebelling against God for such a long time that they are being judged and sent into exile, almost like a prison sentence, but then God says after this time I will bring you back into the land of Israel, He says I will confirm my promise to you.
"For I know the plans I have for you," this is the Lord’s declaration. "Plans for your shalom, not for disaster, to give a future and a hope!"
Even though the Jewish people were in exile, God had not forgotten them nor destroyed them. It’s God’s will that held them in a place of exile, there is a reason for it, time to reflect!
70 years, the land of Israel was to rest they were supposed to the let the land rest every 7 years, 490 years the Jewish people had been in the land, and they were to let the land rest every 7th year from an agricultural perspective, but they didn’t.