Here “kingdom” refers to God’s rule as king. See how you translated this in Matthew 4:23. Alternate translation: “the good news that God will show himself as king”
"every disease and every sickness." The words "disease" and "sickness" are closely related but should be translated as two different words if possible. "Disease" is what causes a person to be sick. "Sickness" is the physical weakness or affliction that results from having a disease.