Snapshots are like a "picture" you take of a VM. The most common case uses for them are:
a) backup software like VEEAM.
b) when installing something that you suspect it will break the VM.
In the first case, you dont use them directly, but the backup software does. When you take a snapshot, the main vmdk files of the VM will not be changed, changes are written to delta files. Imagine that you're backing up a file that keeps on changing, it would be a disaster.
The other case is when you're going to install software, updates, etc. that you suspect it will break the VM. You'll use the snapshot much like Word's CTRL+Z if something breaks: you can go "back in time" to the moment you took the snapshot.
As a bottom note: DONT use them for backup.
Btw, why are you suspending/resuming your VM?