Pets can understand some human language to a certain extent, especially simple commands and phrases that are frequently used in their presence. They may associate certain words with actions, such as "sit," "stay," or "treat." Additionally, pets can also pick up on tone of voice, body language, and other cues to understand what their human companions are trying to communicate. However, pets do not understand language in the same way that humans do and their understanding is limited compared to that of humans.