For simple text changes, using a localization file or a plugin such as the LocoTranslate or Say What Plugin. See Translating WP Job Manager for more information.
Use a 3rd party plugin such as https://plugins.smyl.es/wp-job-manager-field-editor/ which has a UI for field editing.
Use the WordPress hooks (filters) which are explained in these articles - Editing Job Submission Fields and Resume Manager: Editing submission fields.