The letters MA ACA represent two distinct qualifications.
The abbreviation MA is used quite generally to indicate a Master's degree in any arts subject (i.e. any non-science subject). It is an abbreviation of the longer term Master of Arts. People often just put these two letters after their name to indicate they have a master's degree. If they want the reader to know the subject of their master's degree they can put that information in words after the abbreviation. So it would look something like this:
The abbreviation used to indicate a master's degree in a science subject is usually MSc, short for Master of Science.
In the UK, if you pass the necessary exams and gain the necessary qualifications you will become a member of the Association of Chartered Accountants. At this point you are allowed to put the letters ACA after your name. This indicates that you are an Associate Chartered Accountant.
In English, it is common for people to list several qualifications after their name in formal documents. For example, a well qualified English language teacher might look something like this:
Bob Smith CELTA DELTA BA(hons) MA PHD