izvestan

1. certain; some
   Posle izvesnog vremena, sve se smirilo. — After a while, everything calmed down.
   Tražio vas je izvesni gospodin Petrović. — A certain Mr Petrović was asking for you.
2. certain; sure
   Njihova pobeda na izborima je skoro izvesna. — Their election victory is almost certain.
   Izvesno je da će cene opet porasti. — It's certain that prices will go up again.

In the sense "a certain" the definite form izvesni is usual; for Russian speakers, it does not mean «известный» (= poznat).