Isaiah 38 is a story in the Bible about a very sick king named Hezekiah. He was so sick that he thought he was going to die. He prayed to God to heal him, and God heard his prayer.
God sent the prophet Isaiah to Hezekiah to tell him that he was going to get better. Isaiah gave Hezekiah some medicine made from figs and told him to put it on his boil. Hezekiah did what Isaiah told him to do, and he got better.
As a sign that Hezekiah was going to get better, God made the sun go back 10 steps on the sundial. Hezekiah was very happy and thanked God for healing him.
So, Isaiah 38 is a story about how God can answer prayers and heal people who are very sick.