<em>Yes, they are moving in opposite direction one to the other.</em>
Explanation:
Velocity is a vector quantity, which means that it has both magnitude and direction. The magnitude shows the size of the velocity, and the direction shows which way it is moving in reference to a chosen reference direction. If the red box is assigned a positive velocity, and the blue box is assigned a negative velocity, as indicated in the question, then it means that the red box, and the blue box, both move in opposite direction to the other.
If you mark off a beginning time and ending time on the graph, then the area under the part of the graph between those limits is the distance covered during that period of time.
