en_tn_lite_do_not_use/mat/17/05.md

behold

This alerts the reader to pay attention to the surprising information that follows.

overshadowed them

"came over them"

there was a voice out of the cloud

Here "voice" refers to God speaking. Alternate translation: "God spoke to them from out of the cloud" (See: rc://en/ta/man/jit/figs-metonymy)