"121" is the k of the function. The k determines how much the piecewise function moves up and down, which is called a vertical translation.
"5" is the b of the function. The b determines if it grows or decays. The 5 made the graph grow by five.
"-3" is the h of the function. The h determines how if the function moves horizontal, which is called the horizontal translation. This brought the graph to the right.