Movement of tectonic plates produces volcanoes. Earth's crust is divided into a number of pieces, called tectonic plates and it is the motion of these plates that results in volcanoes and earthquakes. There can be a number of different types of plate movements, the one that causes the volcanoes is known as subduction. At the plate boundaries, the motion of plates will force one tectonic plate under the other. Now, these plates float over hot mantle (which is solid but can behave as plastic), thus the subducted portion will move towards the earth's interior in will melt in this process and turn into magma. This magma will erupt as volcanoes and spread on the surface.
Movement of a tectonic plate over a hotspot will also cause formation and eruption of volcanoes. Hawaiian Islands are a great example of such volcanoes.
Hope this helps.