अन्वयः

सीतायाम् when Sita, प्रधर्षितायाम् was assaulted, सचराचरम् with all beings animate and inanimate, सर्वम् all, जगत् world, अमर्यादम् crossed all moral law, अन्धेन तमसा by pitch darkness, संवृतम् enveloped, बभूव became, तत्र then, मारुतः wind, न वाति did not blow, दिवाकरः the Sun, निष्प्रभः lustreless, अभूत् became.

M N Dutt

And as she, bereft of the company of Răma in the wilderness, was wailing, saying, O Rāma, O Rāma, that one resembling the Destroyer himself, with the view of compassing his own end, seized her by her hair. On Vaidehi being thus outraged, this entire world consisting of mobile and immobile objects, had its nature altered. A dense darkness enveloped (everything).

Summary

While Sita was being assaulted, the earth with the animate and the inanimate crossed all limits of moral law and became enveloped in blinding darkness. The wind ceased to blow and the Sun, to shine.

पदच्छेदः

प्रधर्षितायां	प्रधर्षित (√प्र-धर्षय् + क्त, ७.१)
वैदेह्यां	वैदेही (७.१)
बभूव	बभूव (√भू लिट् प्र.पु. एक.)
सचराचरम्	सचराचर (१.१)
जगत्	जगन्त् (१.१)
सर्वम्	सर्व (१.१)
अमर्यादं	अमर्याद (१.१)
तमसान्धेन	तमस् (३.१)–अन्ध (३.१)
संवृतम्	संवृत (√सम्-वृ + क्त, १.१)

छन्दः

अनुष्टुप् [८]

छन्दोविश्लेषणम्

१	२	३	४	५	६	७	८
प्र	ध	र्षि	ता	यां	वै	दे	ह्यां
ब	भू	व	स	च	रा	च	रम्
ज	ग	त्स	र्व	म	म	र्या	दं
त	म	सा	न्धे	न	सं	वृ	तम्