The first term is $\hat\beta$ itself (with a "T" missing, see comment of @Peter), the second term is the objective function that is minimised by it (so the second one is not $\hat\beta$, although required to define it). In fact it's not exactly the objective function, as factor $\lambda$ is missing before the sum (it's the objective function for $\lambda=1$).
Christian Hennig
- 28.3k
- 35
- 101