If a vacuum cleaner is broken, it may not function properly or at all, depending on the extent of the damage. In the context of a typical vacuum cleaner, "sucking" refers to the process of drawing in air and debris to clean the floor or surface. If the vacuum cleaner is broken and unable to create the necessary suction, it will not effectively pick up dirt and debris as intended.
In some cases, a broken vacuum cleaner may still make noise or show other signs of attempting to work, but if it cannot generate suction, it won't be effective at cleaning. If you encounter a broken vacuum cleaner, it's best to have it inspected and repaired by a professional or consider replacing it if it's beyond repair.