How to change Standard Field Labels
A Salesforce field has three parts in its name - the Field Name which is the unique name of the field (for example, FirstName, or Custom_Field) the Label, which is what users see on a page layout (for example, First Name or Custom Field) and the API Name which you would reference in integrations or formulas (for example, FirstName or Custom_Field__c). It's not advisable (and often not possible) to change the Field Name or API Name, but changing a Field Label is trivial and can often improve user adoption with little impact on functionality.
- How you can tell that a field came from a Managed Package. Look for the icon and the fact that there's a defined Namespace (that will become part of the API Name)
- Field Label - what appears on page layouts for users to see
- Field Name - the unique name which has no spaces or special characters
- Field API Name - the integration name, which is the namespace prefix, followed by the complete Field Name and __c (to mean it's a custom field)
Renaming Standard Field Labels
Renaming Managed Package Field Labels
You'll notice that while you can rename custom objects in the above screen, you can't rename Fields there. Instead, you have to leverage a feature called Translation Workbench in order to change Field Labels on managed packages (fields that are noted as Managed and have a namespace)
Go to the Translation Workbench in Setup and select Translation Settings if this is the first time you've used this feature.
Now you can select Override to make your changes. Follow the steps here to rename managed package field labels.