According to the hints "שום דבר" means "nothing." And we learned earlier that "לא" is a negation. So, does this mean that Hebrew is like the Romance languages, in that the grammar wants for a double negative?
Czech - slavic language - has is too and there lived great many jidish speaking jews.
Am i right that if i use שום דבר without the second negation, it mean anything?
Correct. Many Israelis today started adopting English grammar for whatever reason, saying שום דבר עוזר, but this is wrong.