The S’s are nomenclature for what we call power states by Advanced Configuration and Power Interface AKA ACPI.
From most awake to off:
S0: fully on using it in real time
S1: when you idle but your computer is still on
S2 modern idle: it’s similar to s3, except your networking stuff is on, and this unfortunately also governs your CPU output which by default is set to low, but it’s going to be based on the networking demands imposed.
S3: suspend to ram is what USED to be sleep on Windows. It would turn off connectivity networking but keep enough power for RAM for faster get to work times.
S4: what is hibernate for us old dogs on windows, it converts the working memory of your RAM into a file on your disk and then turns your PC off completely. Upon reboot, your PC will read everything from the file and toss it back onto the RAM sticks.
This is why hibernate was so power efficient!
S5: off.
So hibernate is good if you want excellent battery life.