If the height is kept the same, then the area is multiplied by 5.
For example, let's say we had a parallelogram with the properties of:
The area would be base*height = 2*3 = 6 square units.
If we kept the height at 3 units, but multiplied the base by 5, then the base is now 2*5 = 10. The new area is base*height = 10*3 = 30 which is exactly 5 times larger than the old area
new area = 5*(old area)
new area = 5*(6)
new area = 30 square units