Praise be to Allaah.
If a woman who has her period enters ihraam, she should do everything that other pilgrims do in Hajj or Umrah, apart from performing Tawaaf around the Ka'bah.
She should delay Tawaaf until she is clean (when her period ends).
Shaykh Abd al-Kareem al-Khudayr
She can make dhikr, make du'aa', recite the Talbiyah and do good deeds. And Allaah knows best.