What does Matthew 21:17 mean?

The blind and the lame came to him in the temple, and he healed them.

But when the chief priests and the scribes saw the wonderful things that he did, and the children who were crying in the temple and saying, “Hosanna to the son of David!” they were indignant,

and said to him, “Do you hear what these are saying?” Jesus said to them, “Yes. Did you never read, ‘Out of the mouth of babes and nursing babies you have perfected praise?’”

Now in the morning, as he returned to the city, he was hungry.

Seeing a fig tree by the road, he came to it, and found nothing on it but leaves. He said to it, “Let there be no fruit from you forever!” Immediately the fig tree withered away.

When the disciples saw it, they marveled, saying, “How did the fig tree immediately wither away?”