Hi doctors, can you tell me what is hallux valgus deformity?

A misnomer: For one. Hallux - big toe valgus - is a position on the frontal plane where an object is everted. In podiatry this is often the term used to describe a big toe being directed at the mpj towards the second toe. Sometimes referred to as a bunion (again, not entirely true.).

Complex...: Deformity of the great toe and its metatarsal. The 1st metatarsal is deviated away from the rest of the forefoot bones (abducted), and the great toe (hallux) runs over the 2nd toe, sometimes overlapping/ underlapping it in the more severe cases.

Bunion deformity: A bunion deformity with an external rotation of the big toe.