The -d flag in the command git branch -d feature-1 is used to delete a local branch named feature-1. This command will only delete the branch if it has already been fully merged into the current branch or the branch you are currently on. If the branch has unmerged changes, Git will prevent the deletion and display a warning message.
If you want to forcefully delete a branch regardless of its merge status, you can use the -D flag instead, like this: git branch -D feature-1.
