Well, 'new' simply means something that has recently come into existence or been discovered. 'Synonyms' are words that have a similar meaning to other words. And 'novel' can refer to something new and original, especially in the context of an idea or a work of art. For example, a 'new' car is just a recently made vehicle. But a 'novel' concept in car design would be something really creative and not seen before. 'Synonyms' for 'new' could be 'fresh' or 'recent'.
You can say 'This new idea is really novel.' Here 'new' shows it's something fresh and 'novel' emphasizes its originality. For synonyms, you could say 'We need to find synonyms for the word new.' This simply means we are looking for other words that mean the same as 'new'.