Its pretty easy to create a database backup... For example if you are using wordpress or any other CMS then you will find a lot of plugins which can do this for you... For that my preference is to use the -
duplicator plugin...
Another way you can do that is to setup a schedule task on your server (but you will need to access cpanel to set that up as a cron job) which dumps the data to a location of your choice i.e. folder on server, dropbox etc... There are various scripts for that which you can find online and adapt for your own use... If you are having problems with setting something like that then I recommend contacting your webhost - as I am sure they will be delighted to help, offer guidance on that matter...
Finally the other approach would be to code it your self i.e. PHP script which connects to your database and dumps the data to a SQL file or format of your choice i.e. CSV, XML etc....
In all cases make sure you consider security aspects to avoid your data being accessible/stolen...