Stanza 1 Summary

Get out the microscope, because we’re going through this poem line-by-line.

September rain falls on the house

We begin with some very straightforward scene-setting, almost like a stage direction. We immediately know what time of year it is.
Plus, it's raining.
We also know that there's a house involved—maybe a home? In any case, it's a very specific house. Our speaker could have said, "September rain falls on a house," but, instead, she says, "September rain falls on the house." This is a special house. We're going to get to know the folks who live in it, we bet.

In the failing light, the old grandmother
sits in the kitchen with the child

Here, we have more scene-setting, and it's becoming more specific. We're in the kitchen.
"Failing light" indicates that it's the end of the day. This is an interesting way to say that the light is fading, setting up a sad or negative tone for the beginning of the poem. Our speaker could have said something like, "night is coming fast!" or "the sun is setting," and the tone would be more positive, no?
Finally, we have characters. Specifically a grandmother and a child (most likely the grandchild).

beside the Little Marvel Stove,
reading the jokes from the almanac,

Our speaker gives us more specific location, more scene-setting. As readers we're getting more and more inside the place our speaker describes. We get to look around at all of the things there, and see what these characters are doing.
A Marvel Stove is just an old, fancy type of stove. Check it.
Jokes from an almanac? This is a little weird because an almanac is based on facts, but maybe they're just goofing off, transforming facts into something more amusing.
To be fair, while an almanac is a book published once a year with cool facts having to do with the year ahead, sometimes they had a joke or two.

laughing and talking to hide her tears.

Things take a turn for the sad, here.
At first we think the grandmother and child are happily joking around, then we realize the grandmother, at least, is just pretending.
The beginning of the poem started out with rain and failing light, and we're back on that bummer track again.