This would mean "What is the date tomorrow?"
Cual es la - What is the
feche de - date
manana - tomorrow
(Sorry, my computer doesn't support accent marks)
To reply, say "The date tomorrow is [DATE]"
For example, to say The date tomorrow is April 1st, it is:
La fecha de mañana es uno (1) de abril.
(Remember in Spanish, they don't capitalize months.)