Aaron’s rod buds.
The idea is that now the people will clearly see (how have they not already?) that God has chosen him as the one to serve Him. Then, finally, they’ll stop complaining against Aaron which is really complaining about God.
Basically the next verse is them complaining again that no one can go hear the tabernacle w/o dying. They’re scared of God… which is good… but they’re still basically complaining.
Humans are all the same.