HACS is the Home Assistant Community Store that provides a mechanism for installing and managing community integration and custom dashboard cards. You can learn about installing and using HACS here. Once installed, you can use HACS to install the Apex Charts custom card.
Lovelace is the old name for dashboards. You have a default dashboard called Overview and you can create your own.
Awesome, had read lots of stuff but not realised Lovelace was a legacy name, no wonder I got confused.
Got HACs installed, and then installed APEXCards, I had installed manually fine. The eventually issue resolved with the where to install the resources: line which is no longer in configuration.YAML but in the dashboard resources section.
But your info definitely got me closer.
thanks
Dave