my Mac air battery doesn't seem to be charging

FYI, it helps if you would provide the exact model of your Mac since different models require different advice.

You can try running the Apple Diagnostics to see if any hardware issues are detected.

If it is an Intel Mac, then try an SMC Reset.

Check your charger, cables, and ports (choose the article that matches your laptop):

If your MagSafe cable or power adapter isn't working - Apple Support

If your USB-C power adapter isn't charging your Mac notebook - Apple Support

If none of this helps, then have Apple or an Apple Authorized Service Provider examine the laptop to provide you with a repair estimate.