הַמַּשְׂבִּ֣יַע בַּטּ֣וֹב עֶדְיֵ֑ךְ תִּתְחַדֵּ֖שׁ כַּנֶּ֣שֶׁר נְעוּרָֽיְכִי׃
Siya na bumubusog sa iyong bibig ng kabutihan, kaya't nababago ang iyong kabataan na tulad ng agila.
Rashi
that your youth renews itself like the eagle Like this eagle, which renews its wings and feathers from year to year. There is a Midrash Aggadah about a kind of eagle that returns to its youth when it becomes old.