A Hebrew phrase, denoting the whole of humanity in its imperfection. See Gen 6:12; Psa 65:2; Isa 40:5, etc.
That He should give eternal life to as many as Thou hast given Him (ἵνα πᾶν ὃ δέδωκας αὐτῷ, δώσῃ αὐτοῖς ζωὴν αἰώνιον)
Literally, that all that Thou hast given Him, to them He should give eternal life. All (πᾶν), singular number, regards the body of Christian disciples collectively: to them, individually.