I work with quite a few small businesses who run their sites using WordPress. WordPress is a great platform for small and even large businesses, but we do need to keep the site updated.
The biggest reason I see for sites going down is due to updates not being performed regularly. I recommend a cadence of about once a week. No site is 100% secure, but WordPress and its partners try to plug holes as soon as they find them.
Here is a quick video on how to update your website plugins if you are using the WordPress platform for your business.
One important note: Make sure to keep your site and database backed up on a regular basis. Many web hosting providers offer this as a service. Not a bad idea to check if your hosting partner offers backups.
If you have questions or need help, do not hesitate to contact me.
Have a great day!