it means whatever whoever wrote it thinks it means, but I'd assume it's something like "I summarized the events that take place in my own words, and this is not a very 1-to-1 translation of the original work"
Afaik, a summary is basically read by someone capable of understanding the language and interpret by their own words. A translation, be they MTL or paraphrase and checked by editors, often stick close word by word and this may lead to whacked out sentences.
It happens a lot in medsos, I read many about korea's novel (raw summary) so basically just spoiler for you who couldn't bear waiting for translator
Summary are simply just like the word itself, it means that it was a summarized version of the chapter based on the interpretation of the poster
Summary is like when you wrote diary before bed, so you will write everything you do that was eventful or worth to write But translation is like you're writing every single thing when you do something, and when you met and talk to someone you wrote every single thing they said Ex: Mia: could you please help me Me: yes And then I help Mia But summary will be Today I help Mia. So basically same event but one more descriptive and detailed one and other are the main point that happen.