This Spanish phrase is used to indicate a point in time or a limit beyond which something will not or cannot happen. It is often used to express a deadline or a point of no return. It can also be used to indicate a point of completion or the end of a process.
From Wikipedia
The hasta was the spear carried by early Roman legionaries, for which the Roman soldiers known as hastati were named. In later republican times, the hastati were re-armed with pila and gladii, and the hasta was only retained by the triarii. The hasta would also be reintroduced in the Late Roman army in conjunction with the spatha.