to disentangle; to untangle; to unravel; to loosen
to break up into pieces; to pick apart; to flake (a fish)
to relieve; to ease; to relax
「解す」 has other readings with different meanings.
肩の筋肉をほぐしてもらった。
I had my shoulder muscles loosened.
緊張をほぐすために深呼吸した。
I took deep breaths to relax tension.
絡まった糸をほぐした。
I untangled the knotted thread.