Chinese characters with pinyin transcriptions. The marks over the pinyin characters tell you how to control the tone in your voice when you speak the word.
mā - high (1st) tone
má - mid-to-high rising (2nd) tone
mǎ - hi-lo-hi 'dipping' (3rd) tone
mà - mid-to-low falling (4th) tone
ma - normal tone for your voice