en_tn/sng/01/17.md

The beams of our house are cedars; our rafters are firs

The woman describes the forest as though it were a house in which they were lying down. (See: rc://en/ta/man/translate/figs-metaphor)

beams ... rafters

Possible meanings are 1) "beams" refers to large logs used to support everything above the walls and "rafters" refers to the large pieces of wood to which the roof is attached or 2) "beams" refers to the rafters and "rafters" refers to the strips attached to the beams, onto which the builders attached the roofing materials.

cedars ... firs

Cedars were large and strong trees. The word translated "firs" is a general term for trees like cedars but smaller. If cedar and fir trees are unknown in your area, you could use general terms for the tallest and strongest trees. (See: rc://en/ta/man/translate/translate-unknown)