Translation:Who is looking for the big cow and the big wolf?
For the same reason why in Latin there are 15 ways to say "this" (and 15 more ways to say "these").
Czech being an inflected language means that different endings mean different things. These aren't different words, they're actually inflected variations of the same word with different endings for different contexts. Native English speakers typically aren't used to this because English doesn't have much inflection - such as, for example, having only one form for the word "big". Inflection gives us "this" versus "these" (the singular "this" inflected to show plural) and "velký kluk" versus "velká holka" ("big boy" versus "big girl", inflected to show grammatical gender).