The poem is a single line, and it works like a quick, bitter joke that isn't really a joke. The speaker compares something small and ordinary, drinking a cold coffee, to something huge: facing a life that feels useless.
The comparison makes sense if you think about what cold coffee is. It was made to be warm and enjoyable, but it has been left too long, and now it's flat and a little unpleasant. You can still drink it, but the point of it is gone. The speaker seems to feel the same about their own life: still there, still being swallowed one day at a time, but without the warmth that would make it worth anything.
The mood is tired and quietly sad. Nothing dramatic happens. The poem suggests that despair often sits in plain moments, like a forgotten cup on a desk. The short, flat statement, with no exclamation or explanation, makes the feeling seem even heavier, as though the speaker is too weary to say more.