Let:
$V_T$ be the value of the firm at time T
$S_T$ be the value of equity at time T
$F$ be the face value of the bond

At time T,

$$S_T = \max(V_T - F, 0) = \max(50 - 60, 0) = 0$$

What this means is that equity holders receive something if the value of the firm exceeds the face value of debt at time T, otherwise the value of equity is zero. In other words, equity holders receive something if the value of $V_T - F$ is positive, otherwise they receive zero.