Formula on conference t-shirt: $\ell(\beta) = \sum_{i=1}^{N}y_i \sum_{k=0}^{K}x_{ik}\beta_{k}-\log\left(1+e^{\sum_{k=0}^{K}x_{ik}\beta_{k}}\right)$

Question

I need some assistance figuring out what this formula signifies and what it does. It is from a shirt I got recently at a conference and am curious about it. Thanks!

$$\ell(\beta) = \sum_{i=1}^{N}y_i \sum_{k=0}^{K}x_{ik}\beta_{k}-\log\left(1+e^{\sum_{k=0}^{K}x_{ik}\beta_{k}}\right)$$