it means that you turn modules on and off and configure the whole system from a single git repo. it's declarative in that you don't write scripts, just provide the features you want turned on or turned off. I've been using it for years and at least as a professional it's much better. idk about as a layperson. there's a steep learning curve the second you have to like write a custom package or something. if you're a developer, I'd try it out as an env manager for code projects first - it's one of the most useful features the package manager provides.