Encoding in psychology is the first process of perceiving and learning new information. Semantic encoding is a subset where the meaning of a piece of information, like a phrase or picture or word, is encoded rather than just the sound or visual or feeling. If we are able to associate a specific meaning with information, then we are able to better store it in memory via semantic encoding.
Imagine a video of someone cheating on their spouse. It sucks right? But now imagine it’s your spouse. Blammo.