The equivalent of a boat getting a fishing net wound around its propeller. Antibodies may also bind together several bacteria into an immune complex. Linking the bacteria together also limits their ability to move and function properly. The large size of the immune complex also makes it easier for phagocytic cells to latch onto it and engulf the bacteria. Bacterial toxins are waste products produced in bacterial respiration.
Different bacteria produce different waste products.
Some may be harmless to us but others are highly toxic chemicals. These molecules can be neutralized by a coating of antibody. The antibody coat physically stops a toxic molecule from coming into contact with cells of the body. The coating also promotes uptake by phagocytes and break down of the dangerous molecules. Viruses are unable to replicate without the use of host cells.