The video shows the explanation of greatest integer function. This video explains this with the help of graphs. The video first describes the basic greatest integer function. This means the greatest integer less than or equal to the number gave. The graph of this function is drawn. The video then shows the variations of this function. The first variation shows the function that replaces the 'x' coordinate with it subtracted by three. This shifts the graph to the right by three units. The second variation involves the subtraction of the function by three units. This shifts the original graph down by three units.