The French future tense talks about upcoming events. While the French future tense has a full set of conjugations, the English equivalent is just the modal verb "will" + main verb.
J'irai au magasin demain
I will go to the store tomorrow.
Ils mangeront dans l'avion
They will eat on the plane.
The French future tense can also be used in si clauses , to express what will happen if a condition is met:
Si j'ai le temps, je le ferai
If I have time, I will do it.