A (letter)
A is the first letter of the English alphabet. Its name is pronounced like the strong form of the indefinite article a. Eh? has the same sound.
Use in English
Examples (the accents show stress and pronunciation: see English phonemes): a is redundant in ëarly, ëarth, dëarth, rehëarse, hëard, lëarn, yëarn, pëarl (cf. heàrt, heàrth, rehëarse) and in Latin and Greek aê: nébulaê, nôvaê, fŏrmulaê, currículum vìtaê, Aêschylus (*êeskiləss). Unstressed in aesthétics BrE aê can sound like í in ít, while in AmE the spelling can be esthétics, and both e’s are pronounced with the é sound.
As âe this combination is rare: Gâelic Ireland (Gáelic Scotland), Ísrâel (cf. Mîchael, where it is unstressed: *Mŷcle), mâelstrom, phâeton (*fâytən), Râe surname (= Rây Raymond, rây light), while Grâeme is pronounced exactly like its more common variant Grâham (*Grâyəm).
a is redundant in some Scottish names: Líndsay, Múrray surname = Mòray Firth cf. Welsh Ánglesey, Manx Rámsey.
And it is redundant in BrE, for most speakers, in words where the suffix -ary is preceded by an unstressed syllable: díctionary, suppleméntary, sécondary, nécessary compliméntary praise = compleméntary together.
In names beginning with Mc- and Mac-, the a, visible or not, is pronounced schwa, except in a few cases, like McEnroe, where, though invisible, it is the main stressed vowel.