This is the 610th most frequent Catalan word.
tindran
The Catalan word "tindran" means "they will have" in English.
Here, 'tindran' is in the negative form to indicate that in the future, the state of 'having leaves' will not pertain to the trees.
Els arbres no tindran fulles a l'hivern.
The trees will not have leaves in the winter.
In this question, 'tindran' is used to inquire about a future state of having time, employing its interrogative form.
Quan tindran temps els nostres amics per venir?
When will our friends have time to come?
The word 'tindran' is used here as the third person plural future tense of 'tenir', meaning 'they will have', to indicate possession in the future.