A' in Shakespeare

Answer 1

In Shakespeare's plays, "A'" typically represents the word "a" or "an" with an apostrophe added to indicate that a letter has been omitted. This convention was common in Early Modern English to signify contractions or elisions. For example, "A' is" would mean "he is," and "A' will" would mean "he will." The use of "A'" in Shakespeare's works reflects the linguistic practices of the time and adds to the poetic and rhythmic qualities of his writing.

Answer 2

If you're talking about the kind of a' that's used like,

"And then my husband--God be with his soul, a' was a merry man--" -Nurse, Romeo&Juliet

It's an archaic abbreviation of sorts. Pronounce it "uh".