Zora Neale Hurston’s Their Eyes Were Watching God begins and ends with the horizon. The horizon is the line between the sky and the earth, or sea, and is the maximum distance that an observer can see. The horizon is therefore a barrier between the known and unknown, a divider between the world of concrete actions and the world of dreams. In the first lines of the text, we learn that, in life, men never go beyond the horizon:

Ships at a distance have every man's wish on board. For some they come in with the tide. For others, they sail forever on the horizon, never out of sight, never landing until the Watcher turns his eyes away in resignation, his dreams mocked to death by Time. That is the life of men.

Men spend their lives either on land or just at the edge of the horizon. The lives of men, therefore are grounded in the visible, concrete world. Men are bound by the horizon, and men, in turn, bind women to the horizon.

Marriage binds Janie, the protagonist, to the world of men. Janie begins life as a virgin, a dreamer. Marriage forces her to give up her dreams of true love:

she knew now that marriage did not make love. Janie's first dream was dead, so she became a woman.

Woman, etymologically, evolved from "wifman," meaning "wife of man" (OED). So in becoming a woman, Janie's life becomes nothing more than a reflection of the man she is married to. As Logan Killick's wife, she becomes a mule, a farmer. As Joe Starks's wife, she becomes a "bell cow," a mayor's wife and socialite. As a married woman, she becomes an accessory in the world of men, unable to make decisions for herself and unable to control her own life and destiny.

Even Janie’s relationship with Tea Cake is far from ideal. Tea Cake, after all, is the one who decides to leave the house during the hurricane. His decision costs him his life. In contrast, Motor Boat listens to no one but himself, stays in the house, and sleeps through the hurricane.

After Janie is exonerated for Tea Cake’s death, she becomes a free woman and is no longer bound to a man. For the first time in a long time, she is free from the limits of being a woman, a wife of man. By the end of the text, she controls the horizon. She controls that line between the known and the unknown, that line that men sail towards and never reach.

She pulled in her horizon like a great fish-net. Pulled it from around the waist of the world and draped it over her shoulder. So much of life in its meshes. She called in her soul to come and see.

Having lived a life dependent on the decisions and whims of men, Janie's ability to manipulate the horizon signifies her independence. Rather than being controlled by men, she now has control over the boundaries that limit the lives of men, who are doomed to "sail forever on the horizon, never out of sight."

Much of the narration in Zora Neale Hurston's novel Their Eyes Were Watching God borders on poetry. As such, it doesn't always lend itself to a simple summary. The passage that you quote seems to me to fit into this category of writing.

One thing that connects this passage with the rest of the novel is the image or metaphor of the "horizon." The horizon, of course, is always far away from us; it is the place where the earth and sky appear to meet. In the novel, the horizon is used to talk about possibilities in life that are ahead of us, perhaps even out of reach.

Janie is often looking toward the horizon throughout the novel. She wants more from life than she is getting. (For example, she agrees to marry someone whom she does not love, and she suffers for it until she finally realizes that she has to move on to find what she wants out of life.) In this passage at the end of the novel, she seems to fully understand her own power to get more out of life. In this passage, she is active and owns her future: she "pulled" it to her and "draped it over her shoulder."

The enotes study guide for Hurston's novel has a section on the themes (see the link below) . In a subsection on the theme "Search for Self," this same passage from the end of the novel is quoted and interpreted as follows:

In the closing lines the narrator tells us, "She pulled in her horizon like a great fish-net," indicating that she no longer has to seek for meaning outside of herself in the world; she has found it within herself.