Post-editing consists of proofreading and correcting, sometimes even reviewing a translated text using a translation machine.
As this text is not translated by a human, it very often contains significant mistakes. For example, the words chosen by the machine may not correspond to the terms of the original text or the area of expertise.
Sometimes it is not even suitable for the target audience or the expected language level.
Post-editing allows these problems to be corrected, so that the text is relevant and it can be understood by the human.