What does Psalm 118:25 mean?

The Hebrew words translated "save us, we pray" or "do save, we beseech You" are hosiāh' nā'. This is recorded in the New Testament Greek as hosanna. This song was used in connection with important feasts in Israel (Deuteronomy 16:16). Among those was Passover. When Jesus Christ entered Jerusalem days before His crucifixion, crowds shouted words from this psalm to celebrate Him (Matthew 21:9; Mark 11:9; John 12:13; Psalm 118:26). As part of that, the people waved palm branches, possibly inspired by an obscure Hebrew phrase later in this song (Psalm 118:26–27).

Those who honored Jesus' entry into Jerusalem understood Him to be the fulfillment of God's promises to send a Savior. The title of "messiah" is from a statement in Daniel referring to an "anointed one" (Daniel 9:25–26). In Greek, the term became Christos, which came into modern languages such as English as "Christ." At the moment Jesus received these praises, He was publicly proclaiming His fulfillment of these prophecies (Matthew 21:4–5; Zechariah 9:9; Luke 18:31). The cries of the crowd, and even of children (Matthew 21:16), were part of Old Testament predictions.

This song has called for praise (Psalm 118:1–4) and celebrated God's work in preserving Israel against enemy nations (Psalm 118:10–13). God's salvation has also been noted (Psalm 118:14–15). This general plea for God's salvation seems to be a request for God to continue to act as He has in the past.