Zero monetary value. A "10,000 dollar" hell bank note (also called joss paper or spirit money) is a ritual offering used in Chinese ancestral worship and Taoist/Buddhist ceremonies. It is not legal tender, has never been issued by any bank or government, and cannot be exchanged for goods, services, or currency.
Some vintage or artistically designed hell notes have niche collectible value (a few dollars to ~$50 on eBay/specialty markets), but the face denomination is purely symbolic. Do not confuse with actual Hong Kong currency (HKD), issued by HSBC, Standard Chartered, and Bank of China under HKMA authority.