Lightroom doesn't support file renaming. You can add titles, captions, and keywords to help you organize your photos and describe the in a way that's visible to you and others if you choose to share the photos. Lightroom is designed to manage and edit your photos without destroying any of the original attributes of the photos. If you want to change the file names of your photos, you would need to do this before importing them into Lightroom. Hope this helps!