Hot spot volcanoes are volcanoes that have been created from hot spots.
A hot spot place deep within the Earth where hot magma rises to just underneath the surface, creating a bulge and volcanic activity.
If you don't get it, imagine a candle flame under a sheet of paper. As you drag the paper over the flame, it creates a brown line where the paper burns. The fire represents a hotspot and the brown line represents the volcanos that have been created by it.