“Hukkua” means “to drown”. “Eno putosi veneestä ja hukkui järveen.” / “Uncle fell out off the boat and got drown in the lake.”
It can also be used in a less dramatic context, the other meaning is “to get lost” : “Pekan avaimet hukkuivat / Pekka’s keys were lost.”.
Note the difference between “hukkua” and “hukata” In linguistics they are called transitive and intransitive verbs: transitive verbs need an object, intransitive cannot have one.
hukkua: “Avaimeni hukkuivat” / My keys were lost.
hukata: “Hukkasin avaimeni” / I lost my keys.