The French a vowel, written with a single letter a, is pronounced in a similar way to the a of English words hat, cat etc as pronounced by many English speakers. It is pronounced with the mouth in an open position and the tongue quite far forward in the mouth, and with the lips unrounded.
Listen to these words
Note that when the letter a is followed by another vowel letter, it usually doesn't represent an vowel, but instead the two letters together represent another vowel. For example, the combination au represents an o vowel.
In what is generally considered to be standard pronunciation in France, speakers use only one "a vowel".
A small number of speakers actually have another a vowel, pronounced with the tongue towards the back of the mouth a little like the vowel in Southern British English pronunciations of car. This second a vowel occurs in fewer places. A notable example is the word pas "not" and cases where the vowel is written with a circumflex accent, â. Thus, a handful of French speakers pronounce the words patte ("paw") and pâte ("paste") differently (but most speakers in France pronounce them identically). In other cases, there is variation among speakers that have both vowels as to which vowel is used where.
Because of the lack of concensus on when it is used, and because most French speakers nowadays have only one a vowel (and this is considered standard pronunciation), learners are generally recommended to stick to a single a vowel.
On the next page, we look at French e vowels.