Your question is somewhat incomplete, but I'll answear anyway. Two things:
- You're not saying how the table is "initially not showing". If there is some - renderedon it, than you need to know that you must render a parent of the table. You can render only things that exist in rendered HTML. See for example this answer.
 
- If you'll put - actionin the button you'll see that the AJAX won't work. You need to change event to- actionor delete this attribute to use a default.
 
I preperend simple working example (BTW. Welcome on Stackoverflow :-) If you want get help faster Minimal, Reproducible Example should be your's part of a question :-)):
(XHTML, added action to commandButton and remove event in f:ajax)
<h:form>
    <h:commandButton id="submit" value="Submit"
        action="#{peliculasEditarBean.initialize}">
        <f:ajax execute="@this" render="listaActores" />
    </h:commandButton>
    <h:dataTable id="listaActores" border="1"
        value="#{peliculasEditarBean.listaActores}" var="actor">
        <h:column>
            <f:facet name="header">NOMBRE</f:facet>
                #{actor.nombre}
            </h:column>
        <h:column>
            <f:facet name="header">APELLIDO</f:facet>
                #{actor.apellido}
            </h:column>
    </h:dataTable>
</h:form>
(and bean)
@ManagedBean
@ViewScoped
public class PeliculasEditarBean implements Serializable {
    private List<Actor> listaActores = null;
    public List<Actor> getListaActores() {
        return listaActores;
    }
    public void initialize() {
        listaActores = new ArrayList<>(3);
        listaActores.add(new Actor("foo", "bar"));
        listaActores.add(new Actor("foo", "foo"));
        listaActores.add(new Actor("bar", "bar"));
    }
    
    public class Actor {
        private final String nombre;
        private final String apellido;
        Actor(String nombre, String apellido) {
            this.nombre = nombre;
            this.apellido = apellido;
        }
        public String getApellido() {
            return apellido;
        }
        public String getNombre() {
            return nombre;
        }
    }
}