غُلْبٌ تَشَذَّرُ بِالدُّخُولِ كَأَنَّهَا جِنُّ الْبَدِيِّ رَوَاسِيًا أَقْدَامُهَا
They are thick-necked, formidable men, ready to enter contention, as if they were desert spirits, their feet planted firmly.
Ghulb, plural of aghlab, describes men with thick, powerful necks. Tashadhdharu evokes aggression or readiness for confrontation; their feet are imagined as firmly rooted.
Comparing them to jinn of the wilderness is poetic hyperbole, not a literal identification. The formidable opponents establish the scale of the speaker’s claimed courage.