The speaker is drinking by himself and wondering where he can find decent company. The answer is a joke with a sour edge: he has to make do with what's in front of him. He describes his father as "a pint of sack," a kind of strong wine, which suggests his father is present only as a drink, or that drinking is something he inherited. He calls himself "a weak sea," which could mean he feels shapeless, restless, and easily pushed around, like water with no real force of its own.
The last two lines turn absurd. He barks in Latin at a dozen bottles of wine, as if giving a speech to an audience that can't answer. The Latin sounds learned and a little ridiculous, and the bottles make a silent crowd. The mood is darkly comic and lonely. The speaker seems to know how silly he looks, and that self-mockery covers a real sense of isolation.