I don't know if you can say the "accent aigu" has a function, it's merely a phonetic mark to change the height of the sound from [e] vowel in French. It's not like a tone or a stress. [e] sounds a bit like 'u' in 'humming' , but [é] sounds more like 'hey'. Wikipedia say it clearly :) The acute is used only on é. It is known as accent aigu, in contrast to the accent grave which is the accent sloped the other way. It distinguishes é [e] from è [ɛ], ê [ɛ], and e [ə]. Unlike in other Romance languages, the accent marks do not imply stress in French