So RAM is just memory space that is accessible very quickly by applications that need it. Many applications use it to just temporarily keep information while you have it open. If you have a lot of applications open or you have an application that stores a lot of things even if it doesn't immediately need it all, you can run out of it quickly.

A swap space is a Linux tool (though there are similar things in Windows) that reserves a spot on your hard disk to move data to and from RAM, to keep data that isn't actively being used off the RAM and data that is being used on it. That way you're not as likely to run out of memory from memory-hogging applications.

There's a separate tool to use Google drive space as a disk in Linux. Then, once it's configured as a disk, you can make it act as a swap space. Of course, this is very slow even compared to normal hard disks, but the point is it is possible to do it.