why does my battery on my macbook say not charging

Refer to Get help with your Mac notebook battery - Apple Support:

If your Mac isn't charging

Confirm the correct wattage AC adapter for your computer. A power adapter rated for a lower wattage than is required for the system might not reliably charge the computer. If you're not sure which power adapter to use with your computer, learn how to find the right power adapter and cord for your Mac notebook.

For more help, learn what to do if your USB-C power adapter isn't charging your Mac notebook. If issues persist, shut down your Mac, close the display for 30 seconds, then try to charge again. Or if you have an Intel-based Mac, reset the SMC.

240v is fine. The power adapters are designed to be used worldwide.