What does the symbol mean?

I have a Huawei, (p20) and have seen that there's a sheet inside the battery symbol. What does that mean? Should I issue it or is it a good thing?

I guess the "energy saving mode"

This is the "save power" mode

Power saving mode

you can switch it off under Settings - Battery

PS: there's also an ultra-energy saving mode, where some apps are restricted

You can leave energy-saving mode like this.

What could be there are problems syncing with Gmail but is not that bad.

The ultra economy mode only allows you to write SMS and make calls.

Yes, but you can also add a gallery etc.

All right.

You can actually leave this "light" energy-saving mode, there are no (hardly) restrictions, your cell phone may not synchronize every app every second, but otherwise…

Your cell phone will gradually turn into a tree