In general we use cardinal numbers to say dates in Spanish, and not ordinal numbers like in English. If we want to refer to a date of an event, we place the definite article "el" before the date (the in English). If we add the day of the week, this comes between the definite article and the date. For example: mi cumpleaños es el 5 de mayo - My birthday is the 5th of May // La pelicula se estrena el viernes 2 de abril - The film is released on Friday the 2nd of April.