Imagine having an awesome collection of Pokemon stickers you ask your friends to exchange some of them with yours. Everything is cool until the very next moment when you find out that your favourite sticker is lost or is dumped somewhere...you are sad now just because of those stickers but then your friends offer you the same sticker with the same Pokemon on it cause they were having the copies of those stickers now you are happy so you go back to your house and keep the sticker somewhere safe so that it never gets lost again.
Here "having an awesome collection of Pokemon stickers" indicates your repositories in GitHub.
When you lost track of what is the status of your repository is indicated by "sticker getting lost or dumped".
But then you have already created branches of your main branch so there you can revert your actions and make the necessary changes in your repository without hampering your main branch