When people say "Chinese", they usually mean Mandarin (普通话 pǔtōnghuà) — the official language of China (including its Taiwan region) and Singapore, spoken by well over a billion people. 人们说的"中文"通常指普通话,是中国(包括中国台湾地区)和新加坡的官方语言,超过十亿人使用。
Unlike English, Chinese is a tone language: the same syllable said with a different pitch means a different word. For example mā means "mother" but mǎ means "horse". 中文是声调语言:同一个音节,声调不同意思就不同。
Chinese writing uses characters (汉字 hànzì) — about 3,500 are needed for daily life, but you only need a few hundred to start reading simple signs and messages. 中文用汉字书写,日常约需 3500 字,但认识几百个就能读懂简单内容。