RAM stands for Random Access Memory. It is a type of computer memory that is used to store data that the CPU needs to access quickly. RAM is volatile memory, which means that it loses its contents when the server is turned off.
RAM is important for performance on a server level because it allows the CPU to access data quickly without having to go to the hard drive, which is much slower. The more RAM the server has, the more data the CPU can store in memory, which can lead to improved performance for your website and other applications.
When a visitor loads your website, the server needs to load the necessary files and execute the PHP code to generate the requested page. This process requires the server to access a lot of data from the hard drive. If the server does not have enough RAM, it will have to constantly swap data between RAM and the hard drive.