Citrus, soapy, mossy, powdery. The cornerstones of men's perfumery back in the day. Nowadays the men's market is saturated with synthetic cloying ambers and airy aromatics, but through the 60s-80s, the citrusy barbershop fragrances were king. And Bois du Portugal is definitely one of the better ones. To the basic fougere formula of oakmoss, lavender, and bergamot, a green, almost vegetal accord is added that gives it more of a sharp edge rather than the more soapy fragrances in the fougere genre. The drydown is fairly powdery woods, further cementing the old school vibe of this fragrance.
And maybe this isn't the right venue to talk about this, but when I say "old school" I don't mean that people under the age of 30 or 40 should be banned from wearing this fragrance. It just means that 1. If you're over 50 or 60 and wearing this fragrance, people will think you've been wearing the same frag since the 70s/80s, and 2. If you're under 30 wearing this fragrance, you are making a statement, similar to wearing something like a tweed sport coat with elbow pads, or a vividly-colored patterned bowtie. As long as you feel you can pull it off, go for it.
In general I'm not a fan of the soapy/powdery "gentleman" scents, but Bois du Portugal has just enough unique green notes to make it stand out. Not worth a full bottle from me, but I can see this being the perfect scent for someone who wants to make an impression on people.