It could simply mean that a biological male body was prepared in advance for Him to inhabit, such that He remained fully God and now also fully human(see below), meaning having a human body.
When I read this passage
“But a body You have prepared for Me.”
I also consider the fact that Jesus did not inherit the exact fleshly body as we inherit from our parents.
“but made Himself of no reputation, taking the form of a bondservant, and coming in the likeness of men.”
The likeness of men, or not identical to men but in men’s likeness. His body was biological, it carried all the markers genetically that would make him a homo sapien / human being but His body did not carry the corruption of Adam, whether that be carried genetically or otherwise.
“And being found in appearance as a man, He humbled Himself and became obedient to the point of death, even the death of the cross.”
Apostle Paul goes further
“So also is the resurrection of the dead. The body is sown in corruption, it is raised in incorruption. It is sown in dishonor, it is raised in glory. It is sown in weakness, it is raised in power. It is sown a natural body, it is raised a spiritual body. There is a natural body, and there is a spiritual body.”
I Corinthians 15:42-44
The natural body we have is corrupted. Is mortal, yes, (but so was Adam’s even before eating of the forbidden fruit) but it’s also corrupted, by sin.
“Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; nor does corruption inherit incorruption.”
I Corinthians 15:50
Whatever body Christ had received it was uncorrupted by sin and it had to be. He had to be an undefiled sacrificial lamb. And when He drank the cup, He drank the wrath of God, not our sins.
“For He made Him who knew no sin to be sin for us(propitiation), that we might become the righteousness of God in Him.”
II Corinthians 5:21
If He inherently had a body that was corrupted by sin, then He could not be a righteous sacrifice.
Jesus had a very curious way of describing Himself.
“For the Son of Man has come to save that which was lost.”
He used it so often it was almost as if He was excited to have taken on human form.
My guess is Jesus was given a body like Adam, God (Jesus) fashioned Adam’s body (without sin, uncorrupted) and the Holy Spirit fashioned a body for Jesus in the womb of Mary (without sin and uncorrupted).
“By this you know the Spirit of God: Every spirit that confesses that Jesus Christ has come in the flesh is of God,”
I John 4:2
Meaning he had a body made of meat
“For there is one God and one Mediator between God and men, the Man Christ Jesus,”
I Timothy 2:5
He was a male huMAN.
“But now you seek to kill Me, a Man who has told you the truth which I heard from God. Abraham did not do this.”
He himself calls himself a human in the Greek
”Inasmuch then as the children have partaken of flesh and blood, He Himself likewise shared in the same, that through death He might destroy him who had the power of death, that is, the devil, and release those who through fear of death were all their lifetime subject to bondage. For indeed He does not give aid to angels, but He does give aid to the seed of Abraham. Therefore, in all things He had to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God, to make propitiation for the sins of the people. For in that He Himself has suffered, being tempted, He is able to aid those who are tempted.” Hebrews 2:14-17
He was human in all ways except without sin
“And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth.”
The Word or the et became a human and lived among humans as a human
“And she brought forth her firstborn Son, and wrapped Him in swaddling cloths, and laid Him in a manger, because there was no room for them in the inn.”
He was born from a female woman, meaning he had to have commonality with her organs to develop and be delivered from the womb.
And just to be clear even further, Jesus has an identical body to Adam, sinless, meat, bones, blood, skin with organs and nervous system and all that the human biological machine entails. It was human in every possible way, just that He didn’t inherit the genes or the markers of sin that altered the genome from generation to generation much like Adam (and Eve, not Cain and Abel) has genetically perfect bodies. Jesus too the second Adam was given a sin free human body.