I saw her swiftly borne away By Rávaṇ’s might which none could stay. I hurried to the lady’s aid, I crushed his car and royal shade, And putting forth my warlike might Hurled Rávaṇ to the earth in fight.

In plain words: Jatayu says he saw Ravana carrying Sita away and rushed to help her. He smashed Ravana's chariot and royal umbrella and knocked Ravana to the ground.