Question: what's the meaning of cologne?
Hello. In this context it means scent/smell/stench/etc. The sentence can also be written:
"Even from the street, I could pick up the six-month-old scent of charred wood and grinding damp where the firemen's hoses had penetrated every seam and crevice."
However, the writer has made an analogy between cologne (aftershave) and the aroma of the remains of a fire. It's purely for artistic merit.
Hope that helps.
spaced