He was oppressed, and he was afflicted, yet he opened not his mouth; like a lamb that is led to the slaughter, and like a sheep before its shearers is silent, so he opened not his mouth.
Jesus could have spoken up in his own defense at his trial, as the accusations against him were false and conflicting. Jesus could have spoken a single word and destroyed his opponents, called down armies of angels or brought himself down from the cross. Think about how outraged we feel when we have false accusations made against us. Even though none of them will come anywhere close to this situation, we are desperate to defend ourselves, to set the record straight. Jesus didn't. He remained silent. He chose the cross.
In Acts 8, the Ehtiopian eunuch is reading this passage from Isaiah and doesn't understand it. Phillip, starting from these verses, "told him the good news about Jesus." (Acts 8:35). Phillip probably said something similar to Peter's reflections on the same theme in 1 Peter 2:22-25
He committed no sin, neither was deceit found in his mouth. 23When he was reviled, he did not revile in return; when he suffered, he did not threaten, but continued entrusting himself to him who judges justly. 24 He himself bore our sins in his body on the tree, that we might die to sin and live to righteousness. By his wounds you have been healed. 25 For you were straying like sheep, but have now returned to the Shepherd and Overseer of your souls.