The SD or SDHC memory card you are using in your FZ53 is locked. This protects your saved photos and videos from being accidentally deleted or overwritten with new photos and videos.
Remove the memory card and switch the lever/pin on the side of the SD or SDHC card from the LOCK position to UNLOCK. Reinsert the SD or SDHC memory card back into your camera and power back on. This message should disappear after 2 seconds.