|advice or advise||
Advice is a noun, which means an opinion that someone offers you about what you should do or how you should act in a particular situation. It's an uncountable noun, so it's always singular.
For example: "I need someone to give me some advice."
Advise is a verb, which means to give information and suggest types of action.
For example: "I advise everybody to be nice to their teacher."
!Note - In British English the noun form often ends in ...ice and the verb in ...ise.