The network interface is the bandwidth. It is thanks to this indicator that you will be able to know the quantity of data received and transmitted by your server, called incoming traffic and outgoing traffic respectively in Quanta. For example, when someone connects to your site, this is incoming traffic.
Memory is used to store short-term information. By way of illustration, it is this element that causes latency on a computer when many tasks are running at the same time. The memory graph is not supposed to vary significantly, and in my experience, memory is rarely a problematic element.
The disk is used to store long-term information. This is where your images are stored.
Similar to memory, this element should not vary significantly over time and should not be a factor that will cause your loading times to explode or your site to become unavailable.