What are lacerations?

Laceration: a torn and ragged wound or cut

It means that a part of the liver has been either cut (which would be unusual) or torn, probably do to trauma such as a fall, car accident, etc.

It can range from minimal to life-threatening. Once the danger of loss of blood has been eliminated infection is always a possiblity. If the wound is very deep it may need sutures also.

with warm soap and water then apply triple antibiotic ointment and apply a bandaid.

A laceration is a cut. He suffered a laceration on his cheek during the duel.