وَتَحفِرُand she digs الأَرضَthe earth إِذاwhen ماemphatic particle مَشَتshe walks
وَتَحفِرُ الأَرضَ إِذا ما مَشَت
كَأَنَّماas though تَحفِرُdig رِجلاهاher two feet
كَأَنَّما تَحفِرُ رِجلاها
And she digs up the earth whenever she walks,
as though her two feet were digging.