A Role or ClusterRole grants permissions through rules. The RBAC Permission Analyzer parses a pasted Role/ClusterRole and summarizes each rule - the API groups, resources and verbs it allows - so you can quickly see what a subject would be able to do.
Wildcard grants (apiGroups/resources/verbs of "*") are flagged as broad. The parser is a small tolerant YAML reader (no external dependency) that handles the block-style manifests produced by kubectl. Nothing is uploaded.