The carrying capacity of any individual biological species is the maximum size of the population which can sustain indefinitely in that environment provided the necessary requirements like food, water and other environmental conditions are available.
The carrying capacity in the graph is the point on the graph where the line of population is horizontal. The graph has the population in y-axis and time period on x-axis. Alternatively if in the carrying capacity graph the line becomes parallel to x axis then it gives the carrying capacity. Here, at the point 2000 on y-axis and starting from 15 months in x-axis is the point of carrying capacity is marked with red horizontal line and green border in the image attached.