(Synchronisation) is the transformation of a movie from its original language into another language. In most countries, foreign movies will be just subtitled or moderated with one or two voices by reading the translation. With a real dubbing, the actors of the original version will receive individual voices of each actor, spoken by local actors in lip-syncing.
And this is the art. You can’t use just the translation as labials and consonants don’t match with the original. It will need a dubbing book writer who will reorder the dialog in a perfect match, without losing the expression and sense of the original dialog. This is not easy and an art of its own.
Germany, France, Spain, and Russia are providing the highest standards of dubbing. Their local voice actors are famous as the original main actors. And acting as a voice actor, placing the dialogues in perfect sync and expression, is also an art that needs to be learned in special workshops. Also, Sound Engineering needs special skills, with Music & Effects, Foley arts, and room simulation.
A real dubbing is much more as the perfectionism of a translation. Movies and series are getting a new charm because you are adding part of your own culture to it.