What does Genesis 7:5 mean?

Again in this verse, we are told very simply that Noah did all that the Lord commanded. Faithful Noah obeyed God. Period. That was his lifestyle. His obedience is all the more remarkable to us because of the strangeness of the commands God gave to him: building a massive ark, preparing it to carry representatives of all of the animals of the earth, and then receiving those animals, including birds and insects, as they came to the ship in the week before the rain fell. Noah's prompt obedience was key to his survival: according to verse 13, the preparations were completed just as the waters arrived. Had Noah waited, there would not have been enough time to prepare.

It's not surprising to us that the New Testament writer of Hebrews describes Noah this way: "By faith Noah, being warned by God concerning events as yet unseen, in reverent fear constructed an ark for the saving of his household. By this he condemned the world and became an heir of the righteousness that comes by faith" (Hebrews 11:7). Noah acted in faith. His righteous obedience was evidence of that faith.