A "lamb" is a young sheep. Here is it used symbolically to refer to Christ. See how you translated this in [Revelation 5:6](./06.md). (See: [[rc://en/ta/man/jit/writing-symlanguage]])
"lay down on the ground." Their faces were toward the ground to show that they were worshiping the Lamb. They did this on purpose; they did not fall accidentally.