Since you are new to Linux, some reading will help you to learn the terminology. You could always start with Google and Wikipedia on terms you want to know more about.
To get you started, a Linux system strictly needs only 1 partition obviously. There are cases you don't even need a partition. But for a standalone use at least 1 is minimal (which holds "/" file system). Then you can add partitions as necessary. It's good practice to have /home and swap at least separate partitions. On server setups, /usr, /boot and /var are usually on their own partitions.
As for the swap, it's an area where data from memory can be written temporarily, in order to free up the RAM.
Please take some time to research on your own before asking questions in future.