soqlDatatable: Custom Column Labels - tsalb/lwc-utils GitHub Wiki
By default, the Label for the Field API Name used for the SOQL is used. To override, provide a comma-separated list using the columnLabels metadata property.
Notation uses the Apex Map class's fat arrow notation (=>) for mapping the API Name to your new label: fieldApiName1=>newLabel, fieldApiName2=>new label with spaces 2.
Custom labels are trimmed before being displayed, thus all four of the below are valid ways to supply labels:
fieldApiName1 =>newLabelfieldApiName1 => newLabelfieldApiName1=> newLabelfieldApiName1=>newLabel