In these verses Peter quotes a passage from the prophet Isaiah relating to what he has just said about them being born of imperishable seed.
The word "flesh" refers to humanity. The prophet Isaiah compares humanity to grass that grows and dies quickly. AT: "All people will die like grass dies, and all their" (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-simile)
Here the word "glory" refers to beauty or goodness. Isaiah compares the things that people consider to be good or beautiful about humanity to flowers that die quickly. AT: "goodness soon stops, just as flowers soon die" (See: rc://en/ta/man/translate/figs-simile)
"Word of the Lord" here is a metonym for the message from God. AT: "the message that comes from the Lord" (See: rc://en/ta/man/translate/figs-metonymy)
Here the word "This" refers to "the word of the Lord."
This can be stated in active form. AT: "the good news that we announced" (See: rc://en/ta/man/translate/figs-activepassive)