What does Mark 1:30 mean?

As Simon Peter returns home with his brother Andrew, Jesus, James and John, he learns that his mother-in-law is sick with a fever. The word translated "fever" here is from, the Greek puresso. In this era, people didn't see a fever as a symptom of a disease; they thought of the fever as the disease itself. At this point, Jesus' powers have proved He can exorcise a demon (Mark 1:23–26) and find a lot of fish (Luke 5:4–7). Somehow, however, He has engendered Simon Peter's trust, and immediately, Simon Peter tells Jesus about his wife's mother.

It's often complicated to discuss Jesus' power to heal. It is not always in God's plan to physically heal people, but, like Simon Peter, we should always be willing to ask. Hebrews 4:16 says we can "with confidence draw near to the throne of grace, that we may receive mercy and find grace to help in time of need." The impulsive Simon Peter, who around this same time told Jesus to leave because he feels unworthy (Luke 5:8), now approaches Jesus for help. It's not clear if Peter even thinks Jesus can heal her, but he has to ask. We should have the same trusting boldness when approaching God.