There are essentially two levels of exclusion in CodeScene.
Exclude files, by extension, means that matching file types will not be included in analysis results but they are still considered as part of the project. While they no longer affect Code Health scores or any other metrics, these files will still be part of the "lines of code" displayed on the project dashboard:
Exclude content excludes those parts of the project completely. This is usually used for generated code or assets, or third-party libraries that get checked in. Some users also use this for making a small project out of a large codebase, by excluding everything except the part they are interested in. This is why the "Exclude content" field uses a different kind of glob matching that includes the entire path.