Inhospitable places aren't easy or comfortable to live in, and inhospitable people can be downright unfriendly — even hostile. A hotel is particularly inhospitable if it's got uncomfortable beds and grouchy desk clerks.
Northern Minnesota is inhospitable in January, and many parts of India are inhospitable in the summertime — they are harsh, difficult places for most people. You're inhospitable to a visitor in your home if you don't offer a drink or ask if they want to sit, or in other ways try to make them comfortable. To be hospitable is to be friendly or pleasant, and when you add the "not" prefix in-, you get inhospitable.