Using create custom MatSortHeaderIntl intance to modify the labels and text displayed as an example

create custom provider

*** In app module providers

{ provide: MatSortHeaderIntl, useClass: CustomMatSortHeaderIntl }

*** custom-mat-sort-header-intl.ts

create custom-mat-sort-header-intl.ts and in the file:

import { Injectable } from '@angular/core';
import { Subject } from 'rxjs/internal/Subject';

@Injectable()
export class CustomMatSortHeaderIntl{
    changes: Subject<void> = new Subject<void>();
    sortButtonLabel(id: string) { return `${id} sorting`;};
}