"Advice" is the noun, "advise" is the verb.
Suppose I say to you: "Never be afraid to ask a teacher a question." What am I doing? I am advising you. The words that I say are my "advice" (or "a piece of advice.")
Here are two sentences that mean almost the same thing.
"My advice to you is not to drive in Boston; use the T."
"I advise you not to drive in Boston; use the T."
The "c" in "advice" is a hissing, soft "s" sound; "advice" rhymes with "mice," "ice," "spice," and "dice."
The "s" in "advise" is pronounced like an English voiced, buzzing "z." "Advise" rhymes with "cries," "dies," "buys," and "lies." "Advise" is pronounced as if it were spelled "advize."
A person who has the job of giving advice is an "advisor" (or "adviser," both spellings are used). A college student may go to see her advisor.