Dub localization is when people take movies or TV shows from other countries and change the voices so that they speak in a different language. For example, if a show is made in Japan and the people speak in Japanese, dub localization would change the voices to speak in English instead.
To do this, a team of people called voice actors will watch the show in the original language and then record their own voices speaking the new language. They have to make sure that their voices match the lip movements of the characters on the screen so that it looks like the words are coming from their mouths.
Dub localization can be helpful because it allows people who don't speak the original language to understand and enjoy the show. However, sometimes the translations might not be exactly the same as what the original characters were saying, or the vocal performances might not match the tone or emotion of the original cast. It's up to the dubbing team to try their best to capture the spirit of the show in the new language.