Chinese is like Arabic in that it is an umbrella term for several mutually unintelligible dialects. If all of these dialects are included, there are over 1 billion speakers of Chinese. The two most well-known dialects to people in the UK are Mandarin and Cantonese. Mandarin is the official language of China, Singapore and Taiwan; Cantonese is the official language of Hong Kong and Macau, although Mandarin is also an influential language here and is taught in schools. Mandarin is the language that people learn when they study Chinese as a foreign language.
The spoken language is tonal (ie the voice has to go up or down). Mandarin has four tones: up, down, up-down and flat. Some of the other dialects have many more tones. This is one of the reasons why Chinese is seen to be one of the more difficult languages to learn, because getting the tone wrong can change the meaning of the word! Most words are monosyllabic but there are some compound words.
There are two writing systems, traditional and simplified, which are written left to right. Traditional, obviously, is the original. Simplified was an attempt to improve literacy and has been around since the 1950s. As with spoken languages, there is a split by country between the traditional and simplified forms. Simplified is used throughout People’s Republic of China and Singapore; traditional is used in Hong Kong, Taiwan and Macau. The writing system is pictorial, but contrary to popular misconception it does have grammatical words as well as nouns and verbs.
Although often perceived as a difficult language there are some elements which make it easier, such as a lack of tenses and plurals.