What does a line through my battery mean when I'm trying to charge my

The status bar

displays

saving mode is on.

If that isn't the right "line though my battery" then it indicates an issue with the charging such things as a bad charging cable, charger faulty, bad power outlet, worn battery, dirt etc, in the charging port, or even software glitches.

To fix it:

Try a different charging cable.

Try a different power adapter or USB port (NOT all are powered, and some that are don't supply enough for many phones.)

Look into the charging port, blow it out and or clean it with a soft brush,

You can also see if the cable and charger work on a different device to rule out problems with them.

Software issues might be fixed (usually are) with a soft reset (Reboot it, turn it off then on not just the power button to standby mode)

Good luck.