What is the value of a 1808 the US's First Silver Dollar 8 reales with numerous counter marks?

The fact that it says "U.S. First Dollar" should be an immediate tip-off. No circulation coin would carry an advertising slogan like that. You almost certainly have a replica piece made as part of a set of collectible novelties, and not a genuine coin. The U.S. struck its first silver dollar in 1794 and it was denominated as a dollar, not in reales. A reale was a Spanish unit of currency used on coins that circulated alongside U.S. coins until the 1850s. Coins denominated in reales were issued by Spain and did not have English Wording on them. Furthermore, no U.S. dollars were struck between 1804 and 1835 inclusive.