Or for the confused, the first leur means to them. The second leur means their.
Why leur?? as them?
Yeah "leur" is an indirect pronoun for 'them', while "les" is the direct pronoun for 'them'.
"leur" here means "to them"
As an indirect object pronoun, it means them.
As a posessive adjective, it means their.
Je vais - I am going
leur apporter - to bring them
leur calendrier - their calendar