As already stated, the Latin name identifies a species absolutely where a number of common names exist, ie "all talking about the same thing".
Also, imagine the scenario where NO common names exist (A newly discovered species in a remote area or fossilised remains of an extinct animal) Scientists need to name these discoveries unambiguously.
A mixture of Latin and Greek words are used, perhaps a 'Latinised' version of the discoverer's name (for a newly identified species) is also used.
these latin names are not without reason or, sometimes, humour.
eg bronto-saurus = thunder lizard (greek)
veloci-raptor = speedy robber/plunderer