In other words, if you push an object in the same direction that it is already moving, you are doing work on the object. The amount of work you do depends on how much force you apply and how far the object moves.
For example, if you push a book across a table, you are doing work on the book. The amount of work you do depends on how hard you push the book and how far you push it. If you push the book with a lot of force and move it a long distance, you will do more work than if you push the book with a little bit of force and move it a short distance.