We can find out what she ate for her last meal because her guts are still preserved. She ate a gruel and blackberries for her last meal. We can infer what other people ate in the Iron Age and Bronze Age based on her intestines.   Bog bodies are so well preserved because of no oxygen in the peat bogs. 

They are also well preserved because of the acid in the water. It kills the bacteria that break down the skin, hair, and close on the bog bodies. The bodies look like a leather shoe because they are so old and the acid killing the bacteria. 

Archaeologists can understand a lot about ancient cultures by studying bog bodies. For example, the Tollund Man probably committed some crimes because he had been hanged. The cord is still preserved. 

Archaeologists think that the bogs were used for human sacrifice. They probably had gods that they had to worship. A lot of the bodies were brutally murdered with stab wounds and broken bones. They were likely sacrifices to the gods.