Virtual address space is not RAM. It's an address space. Each page
(the size of a page depends on the system) can be unmapped (the page is nowhere and not accessible. it does not exist), mapped to a file (the page is not directly accessible, its content is stored on disk), mapped to RAM (that's the pages that you can actually access).
Pages mapped to RAM can be swappable or pinned. Pinned pages will never be swapped out to disk. Swappable pages are associated to an area on disc and may be written to that area to free up the RAM they are using.
Pages mapped to RAM can also be read only, write only, read write. If they are writable they may be directly writable or copy-on-write.
Multiple pages (both within the same address space and across separate address spaces) may be mapped identically. This i how two separate processes may access the same data in memory (which may happen at different addresses in each process).
In a modern operating system each process has it's own address space. On 32 bit operating systems each process has 4GiB of address space. On 64 bit operating systems 32 bit processes still only have 4GiB (4 gigabinary bytes) of address space but 64 bit processes may have more. Generally they have 18 EiB (18 exabinary bytes, that is 18,874,368 TiB).
The size of the address space is totally independent of both the amount of RAM memory and the amount of actually allocated space. You can have 100 processes each with 18 EiB of address space on a machine with one gigabyte of RAM. In fact windows has been giving 4GiB of address space to each process since the time when the typical machine had just a few megabytes or RAM.