Taxonomic studies consider a group of individual organisms with fundamental similarities as a species. One should be able to distinguish one species from the other closely related species based on the distinct morphological differences.
Let consider Mangifera indica, Solanum tuberosum (potato) and Panthera leo (lion).
All the three names, indica, tuberosum and leo represent the specific epithets, while the first words Mangifera, Solanum and Panthera are genera and represents another higher level of taxon or category. Each genus may have one or more than one specific epithets representing different organisms, but having morphological similarities. For example, Panthera has another specific epithet called Tigris and Solanum includes species like nigrum and melongena.
Human beings belong to the species sapiens which is grouped in genus Homo. The scientific name thus, for human being, is written as Homo sapiens.