However, this phrase doesn't have a standard idiomatic meaning in Spanish.
To understand what the speaker meant, we need more context. For example:
* If they are talking about a specific thing: "Lo que es bueno en USA, es la comida" (What's good in the USA is the food).
* If they are expressing an opinion: "Lo que es bueno en USA, es la libertad" (What's good in the USA is the freedom).
Therefore, the translation of "lo que es bueno en USA" depends on the context.