What language do they speak in Chile? Spanish? Is English commonly spoken? These are questions I get all the time. Language in Chile is definitely an interesting topic...
It can be incredibly frustrating at times. And it can be incredibly fun as well!
Officially and technically, Chileans speak Spanish. That said, it is a very different form of Spanish than is spoken in Spain or Mexico, or even Argentina or Peru for that matter. It is admittedly fast, sloppy and full of slang. The best analogy I have ever been able to produce is that it is similar to English in Louisiana. If you learned English as a second language in England and then were dropped off in New Orleans, you'd be in trouble. You might have a similar experience in Chile if you learned Castilian Spanish in high school and now want to explore Chile.
Before you're totally turned off there are some important things to know. Firstly, Chileans as a rule are very light-hearted, open and helpful. So while there will definitely be some struggles, usually everyone wants to help - provided you can also be light-hearted, open and helpful. Chileans like to laugh at themselves and each other and if you can do the same, you language barriers will be less significant. Secondly, even though the language is spoken differently, it is written similarly. So street signs and menus, etc. will be much more familiar.
English is often spoken in hotels, especially in Santiago and Pucón; but not 'everyone' speaks English. Many of the people that you would encounter on a daily basis will be excited to practice their English, which normally means something like, "Hello. How are you?" And if you are blond, you might get an, "I love you." The normal rules of travel apply: if you're headed to a touristy place, more people will be used to tourists and different languages. If you want to get off the beaten path and dig deeper into the culture, you should learn the local language.
If you do give Chilean Spanish a whirl, you should be ready for some things like that they drop the 's' off the end of any word ending in s. So, 'gracias' becomes 'gracia.' It will be spoken quickly and a ton of slang will be thrown in. If you tell people to slow down, they will normally think about what they are saying, use simpler sentence structure and drop the slang. For a minute anyway. It's an adventure for sure.