That's the spirit. and You have nailed it.

Are they slang？Is it often used by native speaker？

Question

That's the spirit. and  You have nailed it.

Are they slang？Is it often used by native speaker？

Answer

Both phrases are commonly used by native speakers.

The first one is a bit slang. The second one is very slang as well as metaphorical/figurative.

Answer

Those are idioms, not slang. "Slang" expressions are tied to specific subcultures or are transient or faddish.

Answer

They are colloquial expressions, meaning that they are examples of informal, everyday language.

Answer

I wouldn't say they are slang and they are often used by native English speakers.

Answer

colloquial expressions.