ひとりの少年が羊の群れを追っていた。

one person; alone; unmarried; solitary

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

boy; juvenile; young boy; youth; lad

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

sheep (Ovis aries)

group; crowd; flock; herd; bevy; school; swarm; cluster (e.g. of stars); clump; pack (e.g. of dogs)

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to chase; to run after; to pursue; to follow (i.e. a set order, a trend); to drive out; to oust; to expel; to drive (i.e. a herd); (in passive voice) to be pressed (for time, etc.)