Ms is a title used before the name of a woman to avoid indicating whether she is married or not. Actually, there is no full form for Ms.
Ms. is pronounced as “miz”. It was created in the 1960s, when feminists wanted it to replace Mrs. and Miss. They said it was unfair that women were addressed according to their marital status and men were not. Generally use Ms only when we don’t know the marital status of the woman we’re addressing.