idea
The Italian word 'idea' is used in much the same way as the English word 'idea'. It could refer to a thought or concept, or to a plan or proposition. Like in English, it is a countable noun, so you could have 'one idea' (una idea) or 'many ideas' (molte idee).
I have a brilliant idea.
This phrase is commonly used when someone wants to suggest an innovative solution or proposal. It directly translates to 'I have a brilliant idea.' in English.
This is not a bad idea.
This phrase is typically used to express agreement or positive opinion about a suggestion or plan. The English translation is 'This is not a bad idea.'
I have no idea.
The phrase 'Non ho la minima idea' is an idiomatic expression that means 'I have no idea' in English. It is used when someone has no knowledge or clue about a particular matter.