This is a broad question. What are the implications of the B(El) values, that are used to explain the transition of a nucleus to a state where l units of angular momentum are transferred? What all information can be extracted about a nucleus and its structure if its electric transition probability to various excited states is known?
Strictly speaking, the only thing that can be done is to compare this value with theoretical predictions. We can gain some qualitative insight by comparing to the predictions of somewhat simple models. For example, a rotational model predicts that states in the same rotational band will have a strong B(E2) between them, and a weak B(E2) between different bands. If we measure a string of states with a strong B(E2), then we can interpret them as a rotational band. A second example would be the simple shell model prediction that certain M1 transitions are forbidden. If we measure a small B(M1), then this would support the idea that the given states are she'll model-like.