。
She set the plates on the table.
Literal
She [topic-は] table [genitive-の] top [on-に] plates [object-を] placed.
置く ('place, put, set down') is the everyday transitive verb for putting an object on a surface. The に marks the location of the placing — テーブルの上に ('on top of the table'). Compare with the closely-related 並べる ('arrange in a row, line up'): 置く is the neutral 'put,' while 並べる adds the nuance of orderly arrangement. Useful pair to keep distinct.