Get them to talk (in English). Ask them about their family, how many brothers and sisters, their ages...
It gets them speaking in English without realising it. You could print up the WiFi, on a card, but let them ask for it. It gets them speaking English.
Beware, they may think you're the maid (most of them, vast majority, have maids at home. Plus mother is a glorified maid). It's not easy to explain you're not the maid because their English isn't good enough to understand the nuances. So don't act like the maid..
A lot of them will be struggling with culture shock - where are they from BTW? How old? - so give them some leeway. They're usually young, teenagers, so expect teen behaviour.
Sit down with them and take your time. Chat about their families and your family, their culture, your culture. Insist they speak in English in your home (but don't be a dragon! Make a joke of it ) - that's what they're here for, after all. If they speak in their language it hugely holds them back learning English : it has to be full immersion.
You'll get zero support from the language school, so be prepared.
Be kind but firm.
Play cards together.
Most are terrified of English food - we have a terrible reputation internationally. Prove then wrong.
Talk to them slot. A Lot. English, English, English. Take them to the bus stop, draw them maps, how to get to the school from the bus so, how to get to your house from the bus stop. Get them to buy an English SIM while they're here.
Good luck! It can be great fun but you have to work for it, no mistake.