We need a way to provide power to the STM32. We do this through a pin header that will allow us to connect an external power source to the board. On my schematic you’ll see two blocks which seem to do this purpose. The middle one (J3) is a 2 pin header and the left one (J1) is a screw terminal. I have added both just for convenience.

You’ll see a 3v3 Zener diode. This is just there in case I accidentally plug ground to power and power to ground. Capacitor is there just for filtering.

On the right, you’ll see a bunch of capacitors connected to the power block of the STM32. The STM32 datasheet recommends one 100nF decoupling capacitor for each power pin and a bulk decoupling capacitor.