When we read The Invisible Man, we have to remember that Wells was writing for a different audience: British people in the 1890s. Sure, we can always just use Google to find out stuff we don't already know (for instance, "serviette" means "napkin"). But sometimes Wells' writing seems almost incomprehensible.
The really hard part of The Invisible Man is the way characters speak. A lot of these characters have thick accents. For instance, Mrs. Hall yells out to her husband, "You gart whad a wand?" (6.5). It took us several hours (years, actually) to realize that she's asking him, "You got what I want?" Luckily, it helps that we have some hints in the story to help us decode what people are saying. (In this instance, Mrs. Hall sent her husband to get something and he's taking a while.)
Curiously, the Invisible Man himself speaks pretty normally. So, if the villagers in Iping sound strange to us, you can imagine that they sound strange to the Invisible Man, too. Bottom line: it's okay if you don't understand every word; Griffin doesn't either.