Advice is an uncountable noun, so:
▪ it is never used in the plural
▪ it never comes after an or a number
✗ Naomi Wolf gave me a good advice in her book.
✓ Naomi Wolf gave me some good advice in her book.
✗ They were always there to give practical advices.
✓ They were always there to give practical advice.
Q: How can I refer to a single item of advice, rather than to advice in general?
A: Advice is mostly used on its own or with some.
If you’re worried about it, contact your doctor for advice.
I think you should get some advice from a professional.
You can also say a word of advice, a piece of advice, or (informally) a bit of advice. But none of these expressions is common.
Don’t confuse advice (a noun) and advise (a verb):
✗ I would advice you to choose this company.
✓ I would advise you to choose this company.