advice vs. advise
Advice is a noun: the guidance you give or get ("thanks for the advice"). Advise is a verb: the act of giving it ("I advise you to wait"). They sound different too: advice ends in an s sound and rhymes with nice; advise ends in a z sound and rhymes with wise.
advice
A noun. Guidance or a recommendation — the thing itself. Never takes a plural "s."
- Her advice was to wait a week.
- I need some legal advice before signing.
- That was good advice, badly timed.
- Not "advices" — it is uncountable, so you take a piece of advice.
advise
A verb. To give guidance or a recommendation.
- I would advise against it.
- Counsel advised the board to postpone.
- Please advise when the transfer clears.
- She advises three companies on regulatory matters.
Why advice and advise get mixed up
Advice is the noun, the thing you give or get. Advise is the verb, the act of giving it. The pronunciation differs as well: advice ends in an s sound and rhymes with nice, while advise ends in a z sound and rhymes with size.
English does the same with a few other pairs, such as device and devise, where the c spelling is the noun and the s spelling is the verb. If you can put "some" or "good" in front of it, it is advice. If someone is doing it to someone, it is advise.
One more trap: advice is uncountable. You can give a piece of advice or some advice, but not "an advice" or "advices".
Common mistakes
Can you advice me on which plan to choose?
✓Can you advise me on which plan to choose?
This is the action of giving advice, so the verb: advise.
Thanks for the great advise.
✓Thanks for the great advice.
"The great" comes before a thing, so the noun: advice.
She gave me several useful advices.
✓She gave me several useful pieces of advice.
Advice cannot be counted directly. Use "pieces of advice" or just "some useful advice".
Quick way to remember
Say it aloud. "Advice" rhymes with "ice" and is a thing. "Advise" rhymes with "wise" and is an action. If you can put "some" or "the" in front of it, you want the noun.
Questions
Is it "please advise" or "please advice"?
Please advise. You are asking someone to do something (to tell you or guide you), so it needs the verb, advise.
Can you say "an advice" or "advices"?
No. Advice is uncountable. Say "a piece of advice", "some advice" or "a lot of advice".
Is it "adviser" or "advisor"?
Both spellings are accepted. Adviser is somewhat more common in British English and advisor in American job titles; pick one and use it consistently.
What does "please be advised" mean?
It is a formal way of saying "please note". It uses the verb, advise, because someone is informing you.