AhmedShiboub this is a translation reference. It means the value of the translation named core.ref.save_changes will be used. This system is used for translations that are displayed in multiple places to reduce duplicated text in translation files.
Unless you want/need to provide a different text where the same text was previously re-used, you should leave that reference as-it, and modify the original text. You can search for core.ref.save_changes using the Linguist search field to find and modify the translation that will be used by default.
If you do want to provide a unique translation for that particular place and not re-use the reference translation, write your custom text without starting with =>.
