The sentence 'Voy a aprovechar este trozo de tela para hacerme una falda', is repeated from an above example block, and doesn't match the intent of 'Sometimes we can use "aprovechar" with the same meaning as above but with no direct object.'
Maybe the example sentence at the bottom of the lesson was meant to be included: 'Al cancelarse la clase de español, los estudiantes aprovecharon para irse a tomar una cerveza juntos.', as it isn't shown elsewhere.