Correlation coefficients are ranged between -1 and 1. The example speaks about a large and positive coefficient.
Positive correlation measures the likelihood of two actions taking place together. In this case, it indicates that watching sesame street and other TV programs have been found to happen together in a large proportion of the analyzed cases/individuals.
Correlation does not imply causality. Therefore we do not have enough information to conclude that watching TV actually causes vocabulary enrichment in children.