What does "all in all" mean?

Everything that matters; the only thing of importance.

All in all

Common synonyms include: all, all things considered, almost entirely, altogether, altogether, approximately.

adv, noun

adv, noun ·Uncommon ·Advanced level

Noun

1
Everything that matters; the only thing of importance. uncountable
"[…] to realize, by constant faith, the all-sufficiency of his redeeming power and love — to make him all his salvation and all his desire, the Alpha and Omega of all his hope, his all in all."

Adverb

1
Generally, all things considered modal, not-comparable
"All in all, it's not a bad little restaurant."
2
Altogether, in all, with everything included not-comparable
"There were twenty absentees all in all."
3
Altogether, wholly, in every way archaic, not-comparable
"And I perceived no touch of change, ⁠No hint of death in all his frame, ⁠But found him all in all the same, […]"

Adverb

"All in all, it's not a bad little restaurant."