The chinese language is quite complicated and there are many characters but in order to communicate well you don't need to know any characters and to recognise words you only need to learn about 50 characters.
In the past Chinese people only ever learnt characters but since the 1960's the pinyin system was introduced in which roman characters (letters) were used to transliterate the sounds of the characters. They ended up creating a alphabet similar to the english one but with a few extra letter combinations.
Anyway let me try and explain it my way, you have the original characters and there have always been characters with multiple meanings, these were differentiated by using different tones. So in order to use roman letters there needs to be a tone indicated to determine which word.
There are four tones:
1st tone (high, level, long), indicated by a horizontal bar e.g. ō
2nd tone (high, rising, medium), indicated by a rising accent e.g. ó
3rd tone (low, dipping, long), indicated by a dipping accent e.g. ǒ
4th tone (loud, falling sharply, short), indicated by a falling accent e.g. ò
In theory, this means that each syllable has four different meanings depending on the tone in which it is pronounced.
The syllable ma is a good example
mother mā (first tone）
hemp má (second tone)
horse mǎ (third tone)
scold mà (fourth tone)
question ma (neutral tone)
This makes things complicated especially when there are different dialects, most people dont use correct tones because most words are just put into context.
