More specifically, the quote comes from the personal essay "How It Feels to be Colored Me." Hurston makes the comment in the context of other writers' attitudes toward their blackness at the time in which the essay was written—1928, at the tail-end of the Harlem Renaissance. She says that she does not belong to "the sobbing school of Negrohood," which assumes that her color has given her a raw deal in life. For her, her blackness, as well as her womanhood, is an aspect of her wonderful being. Hurston says that she does not "weep at the world" because she is "too busy sharpening her oyster knife."
As the previous educator mentions, the comment is likely a play on the expression "the world is your oyster." However, Hurston's choice of this expression also alludes to the world's complexity. An oyster is a difficult thing to open, just as the world is sometimes a difficult thing to understand; but, it contains something delectable, if only one is willing to work to get to it. For Hurston, part of that work is being open to experience and not allowing other people's ideas about her to determine who she is and how she moves throughout the world. She is, instead, "sharpening her oyster knife," which suggests a determination to get to the good things that await her.