Breakdown of A vendedora vai trocar o produto por outro.
Questions & Answers about A vendedora vai trocar o produto por outro.
A is the definite article, meaning the.
So a vendedora = the saleswoman / the female salesperson.
In Portuguese, it is very common to use the definite article before a noun, including a person’s role or profession in a sentence like this. Leaving it out is usually not natural here.