how do you say " eleven o'clock"
Although it's not relevant for your specific request, if you specifically want to say "o'clock", you will add "en punto". "A las 11 en punto".
Please pick us up at eleven o'clock tomorrow can be translated as = "Por favor nos recogerá a las once de la mañana.
a las 11 de la manana = At eleven o'clock in the morning.
Son las once (means) = it is 11 O ' Clock a las once means - as others have correctly said - at 11 'O clock.
the expression 'en punto' means/ = exactly, so: a las once en punto = At eleven exactly