Niqab or bur’qu is what a woman wears on her face which has holes for her eyes to see from. It is like Zorro or the ninja mask.
This is forbidden for a woman in the state of Ihram to wear, by the instructions of our Prophet salla Allahu alaihi wa sallam.
However, it is mandatory for a woman in her Ihram to cover her face with a veil that has no holes in it, as long as there are men looking.