。
Trade activity has been declining recently.
Literal
Trade [of-の] activity [topic-は] recently declining-am.
衰えてくる is the ~てくる form of 衰える ('to decline, to weaken') — marking a gradual change that has reached up to the present moment. Contrasts with ~ていく which would signal continued decline into the future. 最近 ('recently') frames the time.