What “A” means
A is one of the hardest-working words in Patois. Before a verb it marks an action in progress ("mi a eat", I am eating). Between two nouns it equates them ("shi a nurse", she is a nurse). At the front of a sentence it adds focus ("a mi do it", it's ME who did it). It also means "to" or "at" before places ("a market").
Examples
Mi a eat
I am eating right now
Shi a nurse
She is a nurse
A mi do it
It's me who did it
How to use it
Used constantly in all registers. Note what it can't do: it doesn't place things (use "deh" for location) and isn't needed before adjectives ("di soup hot").
Where usage varies
"A go" (also written "ago") marks the future: "mi a go buy a car" means "I am going to buy a car".