The object in motion, indicated by the heavy circle at the left side of the image, is undergoing motion with positive acceleration. This means that the velocity of the object is increasing (strictly speaking, becoming more positive). The short line coming off of the top of the object represents the velocity of the object, and is increasing in length as the object speeds up. The object starts off at rest (i.e. velocity is zero) from the origin (position is zero). The first graph depicts the objects position as a function of time, in this case it is increasing at an increasing rate (the "rate of increase of position" is the velocity). The second graph depicts the object's velocity as a function of time, in this case the velocity is increasing at a constant rate (the "rate of increase of velocity" is the acceleration).