Meaning: This sentence tells us that birds were moving through the air above some trees.
Choice of Words: The words "birds", "flew", "over", and "trees" all describe a specific action or object. "Birds" refers to the feathered creatures, "flew" describes the motion of moving through the air, "over" indicates a position above something, and "trees" are the tall woody plants. Together, they create a mental picture of birds soaring above a forest.