Since a lot of this story relies on the literary technique of stream of consciousness (hop on over to our Genre discussion for more on this), we're pretty much swept up in the tides of Granny's mind, rolling along that river of thoughts with her.
Okay, we'll stop with the aquatic metaphors.
The important thing part is that this stream of consciousness makes for a fluid writing style in which one thought flows pretty smoothly into the next, as in the following passage:
She lay and drowsed, hoping in her sleep that the children would keep out and let her rest a minute. It had been a long day. Not that she was tired. It was always pleasant to snatch a minute now and then. There was always so much to be done, let me see: tomorrow (16).
Resting makes Granny think about the long day, which in turn causes her to observe that she's not actually tired, she just enjoys resting. And on, and on.
Of course, just because the writing here is fluid doesn't mean that everything is completely clear. Far from it. Granny's mental activity may appear to flow from one place to another, but that's no guarantee that the thoughts themselves make perfect sense.
What's more, it's so not the style of this story to step in and resolve any confusion that arises for us readers—but honestly, we might actually give this story props for its hands-off approach, since trying to explain everything that's going on would really break up the flow of things. As a result, we're sort of left puzzling over sentences like the following:
She seemed to herself to be Hapsy also, and the baby on Hapsy's arm was Hapsy and himself and herself, all at once, and there was no surprise in the meeting (41).
While this flows along nicely enough, we're probably asking ourselves what in the world it means. That's because it's a pretty ambiguous sentence, one that allows for different interpretations since its meaning isn't entirely clear. If this style of writing gets you a little confused, don't freak out. You're not alone.