Among the main science cases that have motivated the proposal of CUBES, a new high-resolution spectrograph for the Very Large Telescope at the European Southern Observatory, there is the study and the characterisation of the nucleosynthesis of beryllium. Classical novae have been proposed since the '70s as one of the main factories of lithium in the Galaxy, but this hypothesis has been demonstrated on empirical basis only recently thanks to the direct identification of lithium in V1369 Cen and through the observations of the resonance transition of Be-7 II, the Li-7 parent, at 313.0 nm in the near-UV range. CUBES is then the ideal instrument to quantify the amount of Be-7 and therefore of Li-7 produced by the different novae types hosted in the different components of the Milky Way and also in its nearby satellite galaxies. As important by-product of high resolution spectroscopic observations obtained with CUBES, there are the study of the properties of nova ejecta abundances, the shocks evolution in novae and their connection with the high-energy emission observed in these transients, from satellites as Fermi and Swift.