The English language is universally spoken and understood in Australia. However, as Australia is a global melting pot, you will encounter cultures and hear languages from all over the world, especially in the major cities, and you will often find areas and suburbs that mainly reflect the language of their respective immigrant communities. Foreign languages are taught in school, but students rarely progress beyond the basics.
It is rare to find signs in a second language, except in urban areas where there is a large population of Asian immigrants and students, where signs and restaurant menus in Vietnamese and Chinese are common; and also around Cairns and on the Gold Coast in Queensland, where some signs (but not road signs) are written in Japanese or Chinese because of the large number of tourists. On the beaches, some warning signs are written in several foreign languages.
Australian English generally follows British spelling conventions and vocabulary choices, although it is also known for its own colouring and slang. People in rural areas still tend to speak with a strong accent and use some slang words that are outdated in the big cities. Australian slang should not be a problem for tourists, except perhaps in some remote areas of the outback. Australians understand several varieties of English, and you could look foolish if you try to use local slang.
There is very little provincialism in Australia, although accents tend to be broader and slower outside the major cities. Within cities, there is little variation in pronunciation, but it is becoming more common. For example, the word “thou”, which is often rolled across the language, is more pronounced on the south-east coast, almost like “ewe” as opposed to the west coast and other areas. Accent variations mainly reflect the linguistic origin of the speaker.
Visitors who do not have a basic knowledge of English will have a hard time communicating with Australians and should do some planning. Some tour operators specialise in selling packages for Australia tours with guides who speak specific languages.
More than 100 indigenous languages are still known and spoken by Aboriginal people, especially those living in rural communities in the outback and those on the Torres Strait Islands. Because these languages are all different, you won’t find a book of “indigenous” phrases in travel bookshops. Many Aboriginal place names are derived from Aboriginal languages that have been lost, and their meaning is still uncertain. Almost all Aboriginal people also speak English, although people in some remote communities are not fluent in English.
The standard sign language is Auslan (which means Australian Sign Language). When a sign language interpreter is present at a public event, they use Auslan. Users of British and New Zealand Sign Language will be able to understand much, but not all. Auslan and NZSL are largely derived from BSL, and all three languages use the same two-handed hand alphabet. Users of sign languages with other origins (e.g. the French sign language family, which also includes American and Irish sign languages) will not be able to understand Auslan.