ShowHideTabsSections.js

projectTaskSection: function (executionContext) {
    let formContext = executionContext.getFormContext();

    //get tab
    let tabObj = formContext.ui.tabs.get("tab_name");
    //get section
    let sectionObj = tabObj.sections.get("section_name");

    //show the tab
    tabObj.setVisible(true);
    //show the section
    sectionObj.setVisible(true);

    //hide the tab
    //hide the section
    tabObj.setVisible(false);
    sectionObj.setVisible(false);
}