Advice /ədˈvɑɪs/ is a noun and means a suggestion about what someone should do. It is uncountable;
Let me give you some advice: stay away from Margaret.
Not: Let me give you an advice
She gave him a lot of advice, but I don’t think he listened.
Not: …a lot of advices …
If we want to use advice in a countable way, then we use the phrase a piece of advice:
I have two pieces of advice for you about the holiday.
We use the verb advise /ədˈvɑɪz/ to mean ‘to give someone advice’:
I strongly advise you to lose weight.
They finally did what we advised.