What is the purpose of OSC32 in STM32

[LPetr.1]

I am designing my first PCB. I am working on the project that needs low power consumption. For this we chose STM32L031G6U6 microcontroller. After collecting some measurements, the CPU will be put into sleep mode and wake up every minute or so for a few seconds.

I have noticed that the microcontroller has OSC32_IN and OSC32_OUT pins. From what I understand, you can either  connect low speed oscillator (32khz) to these pins or just use this pins as regular GPIO's.

I am trying to decide whether I need to connect 32khz oscillator for these pins for my particular project. I have tried to research but could not find any concrete answers about particular scenarios where would I want to use it. Can someone help me understand what are the uses of 32khz and why should I use this instead of internal oscillator?

[AScha.3]

no, not use this instead of internal oscillator !

OSC32 is for 32khz crystal, for clock. also on battery, at vbat connect 3v3 lipo cell. CR2032 typ.

if you dont need clock/time/date , just dont use it. can use pins for...something else.

[TDK]

The OSC32 pins are connected to the the LSE input, which primarily drives the RTC but can also drive some other things like timers. If you search the reference manual for "LSE" you can see in particular what it's connected to.

LSE cannot be used to drive the cpu clock.