מגדל [מַגְדִּיל֮] יְשׁוּע֪וֹת מַ֫לְכּ֥וֹ וְעֹ֤שֶׂה חֶ֨סֶד ׀ לִמְשִׁיח֗וֹ לְדָוִ֥ד וּלְזַרְע֗וֹ עַד־עוֹלָֽם׃
Great salvation giveth He to His king; and showeth mercy to His anointed, To David and to his seed, for evermore.
Read kabbalistic (mystical) interpretation of Psalms 18:51: and classical mystical sources.