Symbolically the number 3 represents covenants. In the Church we make all of our covenants with our Heavenly Father, in the Name of Jesus Christ and the covenant is sealed by the Holy Spirit of Promise or the Holy Ghost. Hence, the godhead, represented by the number 3, are all involved in the covenant making process.
When a husband and wife are married and sealed in the temple, the covenant is a three way relationship between husband, wife and the Savior Jesus Christ.
In Hebrew, the number three is transliterated into English as: salos
And appears as the following in Hebrew:
The Shin ש is a symbol of the tree of life, burning bush, fire and spirit. Christ is the tree of life as well as the burning bush. Fire and spirit also represent the Holy Ghost. The Lamed ל is a symbol of the staff, word of God or covenant. So the word for the number three in Hebrew is centered with covenant surrounded on both sides by members of the godhead in a three way relationship. In fact, including the number three in Hebrew, most Hebrew words are rooted in three Hebrew letters so that the entire language symbolically reminders us of our covenant relationship we should have with the Father, the Son and the Holy Ghost.
(Just a little appreciation note to my husband who comes up with all the great Hebraisms for us–thanks, sweetie!)