The call that produced the object x is printed, followed by a
three-column matrix with columns Df, %Dev and Lambda.
The Df column is the number of nonzero coefficients (Df is a
reasonable name only for lasso fits). %Dev is the percent deviance
explained (relative to the null deviance). In the case of a 'relaxed' fit,
an additional column is inserted, %Dev R which gives the percent
deviance explained by the relaxed model. For a "bigGlm" model, a simpler
summary is printed.

References

Friedman, J., Hastie, T. and Tibshirani, R. (2008). Regularization Paths for Generalized Linear Models via Coordinate Descent