Ashta siddhi nava nidhi ke dātā, asa bara dīnha jānakī mātā

Mother Janaki(sita) granted you a boon to become the bestower of 8 Siddhis (supernatural powers) and 9 Nidhis (divine treasures)

-Verse 31 of Hanuman Chalisa.

What are the 8 supernatural powers(siddhis) granted by sita to Hanuman?

1. Aṇimā: Ability to reduce one’s size
2. Mahima: Ability to increase one’s size
3. Garima: Ability to become heavier
4. Laghima: Ability to become lighter
5. Prāpti: Ability to Obtain anything
6. Prākāmya: Ability to fulfill your desires
7. Iṣiṭva: Lordship over creation
8. Vaśitva: Control over everything

What are the 9 Nidhis (treasures) granted to Hanuman?

1. Mahapadma: Great lotus flower(one of the nine treasures of Kubera)
2. Padma: Lotus/ a Himalayan lake with treasures
3. Shankha: Conch shell (In Hindu mythology, the shankha is a sacred emblem of the Hindu preserver god Vishnu.)
4. Makara: Crocodile (Makara appears as the vahana (vehicle) of the river goddess Ganga and of the sea god Varuna.)
5. Kachchhapa: Tortoise or turtle shell
6. Mukunda: Cinnabar/ Quick Silver
7. Kunda: Jasmine/ Arsenic
8. Nila: Sapphire/ Antimony
9. Kharva: Cups, vessels baked in fire

Source: blog.cosmicinsights.net/hanuman-sita-siddhi-nidhi/