"carefully remembered" or "joyfully thought about." A treasure is something that is very valuable or precious. Mary considered the things her son did and said to be very precious. (See: [[rc://en/ta/man/translate/figs-metaphor]])
## grow in wisdom and stature ##
"become more wise and strong"
## increased in favor with God and people ##
This could be translated as "people liked him more and more, and God blessed him more and more."