Metro Republique is a central hup for a number of important Metro line which take you either East or West:
Metro Line 3 coming from St. Lazare train station, Opera and going to the Pere Lachaise cemetry.
Metro line 5 coming from Gare du Nord.
Metro line 8 coming from Concorde and going towards Bastille.
Metro line 9 coming from the Eiffel Tower, Trocadero, Champs Elysees.