The first 2-3 Gyr of cosmic history are key to understand reionization and how most present-day galaxies form and assemble. According to recent observations, normal galaxies at these early epochs show more extreme stellar and nebular properties than their lower redshift counterparts, but the connection between these properties and the physical mechanisms facilitating galaxy growth and the escape of ionizing photons used for sustaining cosmic reionization still need to be established. In this scenario, CIII]λ1909 emitters have been proved to be relevant to find out these connections because of their properties similar to primeval galaxies. But their faintness has limited our understanding. In this poster, we present first results on the median physical properties, metallicities and chemical abundances of a large sample of main-sequence CIII]λ1909 emitters at z=2-4 selected from the unprecedentedly deep (exposure times 20-80 h per source) VANDELS spectroscopic survey. Our results can be particularly useful in the near future to interpret the deep wide-field observations with the Roman Space Telescope where these objects are expected to be quite common.