The database log is an interesting feature in AX. It gives you the ability to capture data manipulation as an audit capability. This could in inserting records, modifying records or deleting records. This can also be setup down to a field for example down to a specific field. This video gives you a overview of the concepts in the database log.
While this is an interesting feature for auditing capability use it sparingly because it is working at the data layer in AX so it does mean that for each database operation insert, update, delete etc. There needs to be a respective operation in the database log based on what you have configured. So consider monitoring activities like master file data etc and avoid high volume transactional tables.
As well there are some feature like in purchasing that have application oriented auditing feature like change control that might be worth investigating.