Mary describes her spirit as rejoicing. This word rejoicing is the Greek word agalliaō/ἀγαλλιάω and it's a verb. It is the word that means rejoicing, exulting, as well as possessing exuberance.
This word agalliaō comes from the words agan (which means very much) and the word hallomai (which means to leap).
Therefore, when these two words are glued together, you get a verb that pictures much leaping and bounding. Now it must come without surprise that the word agalliaō also means to show joy with skipping, dancing, and excessive delight.
I find it quite significant that the Virgin Mary chose this word to tell of how her spirit celebrates the Lord. This must mean that every waking moment she would spend with her Savior, her spirit would just leap and bound for joy.
The word Mary used for Savior in this verse is the Greek word sōtēr/σωτήρ and it's a noun. This is one who saves, or a rescuer. Sōtēr depicts one who delivers another from destruction or death and places that other into safety. Pretty powerful word, wouldn't you say?
Sōtēr is used to describe the way Jesus saved us from the ultimate misery and condemnation that is the penalty of sin, and gives us the Lord's blessings and eternal abundant life. Jesus, the Savior of all the world, is the most perfect example of a sōtēr!
Here is how I would rewrite Luke 1:46-49 using this knowledge:
"My spirit leaps for joy and I'm filled with ecstatic, celebratory joy whenever I'm with my Savior. My God rescued me from the consequences of my sins, and He restored my destiny. Now I am redeemed, and a place awaits me in my Savior's Kingdom. I will live abundantly with Him forever. Praise His holy name!"
We all could learn something from Mary here. Are you so intently pursuing the Lord, that your spirit frolics at the thought of being with Him? The more we seek Him, the more we want Him. The more we want Him and really search to know more of Him, the more our spirits will delight in who He is. Every moment is an opportunity to lavish our souls in His love, and to fill our hearts and minds with His truths and promises.
-The Introverted Evangelist