The provided source material does not contain information regarding a city named Yoni in Equatorial Guinea; rather, it describes a religious and symbolic concept within Hindu traditions. A yoni is an abstract or aniconic representation of the goddess Shakti. It is frequently depicted alongside its masculine counterpart, the linga, to symbolize the union of feminine and masculine energies.
In these spiritual contexts, the yoni represents the merging of the microcosmos and macrocosmos, as well as the eternal processes of creation and regeneration. It is conceptualized as nature's gateway for all births, particularly within Shaktism, Shaivism, and esoteric practices such as Kaula and Tantra.