do u need to write report a lot in finance jobs, accounting, financial managers?

Good writing skills are helpful for people who are hoping to work in the financial area.

Im studying Finance right now because I like to deal with numbers, I like math, but my communication skill if not that great so I'm a little not confident about being successful in this Field. Any advice will be really appreciated.

Start writing. A lot. Start reading. A lot.

Seriously consider taking an acting class in order to improve your verbal communications skills, too.

People who excel in the financial field are, as you have already recognized (good for you!), good communicators. It is possible to become one, but it is a skill and you've got to cultivate it.

Writing report is not an easy thing it requires great expertise.

I feel that its not about report writing but about effective accounting.

Financial analysts gather information, write reports, and review all non-legal information. According to me, yes it is necessary for you to write reports if you are in finance field, but it is more important for to have all the knowledge about accounting.
As you said your communication skill is not good so you have to work hard and improve it.