prepreka

1. obstacle; barrier
   Na putu je bila velika prepreka, pa smo se vratili. — There was a big obstacle on the road, so we turned back.
2. obstacle; hindrance; impediment
   Jezik nije prepreka, svi ovde govore engleski. — Language isn't an obstacle, everyone here speaks English.
   Nema više prepreka za potpisivanje ugovora. — There are no more obstacles to signing the contract.

"An obstacle to something" is usually prepreka za + accusative.