。
Please come by anytime tomorrow afternoon.
Literal
Tomorrow [possessive-の] afternoon [if-なら] anytime honorable-come please.
おいでください uses おいで, the polite/honorific form of 'come' (derived from 出でる). It functions as keigo for 来る. Combined with ください, it becomes a polite invitation. なら sets up 'as for tomorrow afternoon' — contrasting with other times.