A treasure is something that is very valuable or precious. Mary considered the things she was told about her son to be very precious. AT: "carefully remembering them" or "joyfully remembering them" (See: [[rc://en/ta/man/translate/figs-metaphor]])
These are very similar and emphasize how excited they were about what God had done. AT: "talking about and praising God's greatness" (See: [[rc://en/ta/man/translate/figs-doublet]])