This poem begins with a confident declaration of what makes a person "happy" (that is, both contented and fortunate). Happiness, in this speaker's mind, isn't anything to do with dazzling dreams of acclaim, brilliance, or wealth. Rather, it's about living a humble, wholesome life on "a few paternal acres."
Those "paternal" acres might suggest that the speaker is talking about inherited land, passed down from father to son. But he might also be saying the land itself has a paternal quality, that it looks after the person who lives on it.
Either way, the speaker is essentially saying that people don't need a lot to live a happy life. Instead, a happy man should be "Content to breathe his native air / In his own ground." In other words, this speaker agrees with Dorothy in The Wizard of Oz: one finds happiness in one's own backyard.
The first lines of the poem are enjambed:
Happy the man, whose wish and care
A few paternal acres bound,
Enjambment launches the reader forward to the (perhaps surprising) idea that happiness comes from a humble life. But this momentum is short-lived: the rest of the stanza (and the vast majority of the lines that follow) are end-stopped. The end-stopped lines reflect the speaker's ideal of a quiet, self-contained life: he sees no point in rushing from place to place, but is rather content to stay where he is and meditate on the virtues of solitude.