The focus here is the brevity of life, and the struggle against death.
In "Out, Out," Frost is juxtaposing the futility of work with the necessity of work. Basically, the boy cuts wood so that the stove in his house can heat the family. Work here means survival, and the boy is just old enough to be helping to take care of the family instead of being taken care of. Work in the poem is futile, though, because it only staves off the eventual oncoming of death, which cannot be stopped. Why work to survive if you're just going to die? That's the poem's basic struggle, and it's an idea that, in some way or another, everyone has to contend with in their lives. Fear not, though, Shmoopers—we're here to help you cut that wood.