Esteban - Normally we would say something like "Show me how brave you are." Hope that helps.:) Cómo se dice esta frase en español?

No, you can't say that in standard English. Normally we would say "Show me how brave you are". However, in recent years there has been a trend in advertising in which an adjective ( such as "better" or "happy") is used instead of a noun. This grammatically incorrect construction is used deliberately to make the phrase more noticeable and memorable. Your sentence is an example of this type of non-standard grammar. But unless your job is devising advertising slogans, you should avoid this kind of construction.