Survival Curve
The basic survival curve is a visual display of the model-predicted time to churn for the "average" customer. The horizontal axis shows the time to event. The vertical axis shows the probability of survival. Thus, any point on the survival curve shows the probability that the "average" customer will remain a customer past that time. Past 55 months, the survival curve becomes less smooth. There are fewer customers who have been with the company for that long, so there is less information available, and thus the curve is blocky.
The plot of the survival curves for each covariate pattern gives a visual representation of the effect of Customer category. Total service and Basic service customers have lower survival curves because, as you have learned from their regression coefficients, they are more likely to have shorter times to churn.