Rester is ‘to stay’, but it’s also…

My students are always at a loss when they’re trying to say:
‘How much time have we got left?’ ’We didn’t have time left’ etc.
The structure is very different in French:
Il me restera du temps: I will have time left
Il te restera 2 heures: you will have 2 hours left
Il lui restera 100 euros: he/she will have 100 euros left
Il leur reste 2 billets: they have 2 tickets left
Il nous restera un peu de crème: we'll have a bit of cream left
Il vous restera un peu d'énergie: you will have a bit of energy left.

It always starts with 'il' and depending on who is talking, you amend the pronoun preceeding the 'rester' verb.

A few examples in the past:
Il me restait 1h pour prendre le train. I had 1 hour left to take the train.
Combien il vous restait de temps? How much time did you have left?
Combien il vous restait (d'argent)? How much money did you have left?
Combien il vous restait de kilomètres? How many miles did you have left?

Others examples:
Il te reste de la peinture? Do you have paint left?
Il nous reste 3 exercices à faire. We have 3 exercises to do.
Il vous reste 3 mois à faire. You have 3 months left to do. 
Il t’en reste combien? How many have you got left?
Il nous reste combien de temps? How much time have we got left?
If you hear someone French start a sentence with ‘du reste’, it means: besides/moreover.
And ‘des restes’: means ‘leftovers’. We know the difference because of the articles – ‘du’ and ‘des’ sound very different to a French person.
Last but not least, ‘to rest’ is ‘se reposer’.
At the weekend, I rested: Ce weekend, je me suis reposé(e).
Se reposer is a reflexive verb, hence ‘je me suis…’