I've mentioned in the previous question a few days ago that advice is an uncountable noun. I've seen when the noun is attached with an adjective beside it, there are some that have article a and some don't
A question taken from an English grammar app verifies my question, but since it's an app, I'm still not sure. Anyway, this is the question and there are only 3 options:
My father gave me __ excellent advice.
The answer key is an. Why is it not the and why does it need an additional article when the verb advice is uncountable?