The title sets up a legal idea: a plea bargain is a deal where you accept a lesser punishment to avoid a worse one. The poem borrows that feeling of bargaining under pressure. The speaker hears only "half a beat / of drum," a sound that seems incomplete, and links it to "serve time," as if the drumbeat were marking out a sentence. In response, the speaker has only "half a hope," which is enough to keep going but not enough to feel secure.
The last two lines turn in an unexpected way. "In the meantime" suggests waiting, a stretch of uncertainty before anything is settled. Instead of resisting, the speaker says to "praise God / for this confusion." That could be sincere gratitude, a kind of surrender, or a wry shrug. The poem doesn't say which. The mood is hushed and uneasy, but there's a flicker of acceptance too. Not knowing is painful, yet it also leaves room for hope.