Is this a idiom the rain was coming down in sheets, obscuring (blocking) the view of far-off cabins and enveloping the distant wood in a gray mist.

No its imagery, its describing the setting

the difference between an explicit and implicit meaning is that the explicit meaning of a poem is that the detail is exactly defined. nothing is left to interpretation. an implicit meaning is an implied meaning. kabir's poetry is both explicit and implicit in that it can be interpreted on different levels. the explicit meaning leaves nothing to interpretation while the implicit meaning leaves lots open to interpretation. an example of this is found in the poem "rumi and the spiritual lover".