What is the correct meaning and translation of the last line of Adon Olam: ועם רוחי גויתי
Sefaria translates it as:
וְעִם רוּחִי גְּוִיָּתִי. ה' לִי וְלא אִירָא: And with my spirit is my body; G-d is for me, and I will not be afraid.
It refers to Tehillim 31:6:
Into Thy hand I commit my spirit: Thou hast redeemed me, O Lord God of truth.
And Rashi on that verse explains this as follows:
I always entrust my spirit because You redeemed me from trouble.
Similary, this prayer teaches us that our souls are contained in the hand of G-d, as the Mekhilta d'Rabbi Yishmael explains (15:12:1)
(Exodus 15:12) "You inclined Your right hand — the earth swallowed them up.": We are hereby apprised that all of the souls are contained in the hand of the Holy One Blessed be He, viz. (Iyyov 12:10) "In His hand is the soul of every living thing", and (Psalms 31:6) "Into Your hand do I commend my spirit."
Loosely translated - When my Neshama returns into my body. This verse completes the cycle mentioned before in the Piyut, first Hashem takes the Neshamos to Him at night and then returns them into our bodies. See Siddur Hameforash by Rabbi Yakov Weingarten, Gefen Publishers and here.