"Hosanna" is a combination of two Hebrew words that trace back particularly to Psalm 118:25, where it is translated into English as "Save us." The words are Hoshiyah-na. The "na" is simply a term of plea, often translated "please." Hoshiyah is the "save us" part, and it comes from the verb "yasha," which is the root word of the name Yeshua, which is Jesus. Personally, I think it is amazing that as the people that Palm Sunday, "Hosanna!" they were actually shouting the name of the one who would save them. He is indeed salvation.