Hi, I never made manual white balance with the G5 yet. I'd like to buy this gray card:
https://www.amazon.it/Kaavie-bilanciamento-impermeabile-portatile-staccabile/dp/B00L1R0B1O/ref=sr_1_15?ie=UTF8&qid=1518039796&sr=8-15&keywords=cartoncino+bilanciamento+del+bianco
I will use it in my trips in Africa but it seems really a small size. Do I have to keep it with my hand or can I put it on the ground? How can I use it if I'm always alone? Is it better ExpoDisc for me? Thank you.

the expodisc is easier to use as you can place it on your lens to whitebalance, a grey card you have to hold in front of a camera, the expodisc also has a strap attached to hang around your neck when not in use + it's made of more durable materiable then greycards.
I only use my expodisc in more challenging light conditions when I"m not sure a preset is ok but otherwise it's either a preset or I dial the kelvin in myself and judge on the screen if I"m close enough.

Ok, but can you tell me if expodisc gives the same outcome llike a grey card in outdoors?

The expodisc will give you a neutral white balance, if you think a grey card is better or easier then just get that, both tools will help you in getting a better whitebalance.

In my opinion expodisc is easier to use. But I don't understand if it is gives different risult than a grey card for white balance. If you use expodisc I need to as:
if I am outside I need to point the camera towards the sky near sun.
But if do I have to shoot people inside a hut? Can I point the camera towards the entrance without the door?

Hello, I just got a new lens Lumix 14-140 mm and I noticed that it doesn't have a switch button like the Leica lens 12-60 mm to put it in manual. How could I use it in manual?
Thank you

There is a switch on the back of the camera body that changes the focus from AFS/AFF to AFC & to Manual. When you have it in manual, you will be able to focus manually with the lens.
If however, you are talking about changing the aperture manually, then you must be in one of the manual modes, & adjust the aperture via the top wheel just behind the shutter button.
Hope that helps.

Thanks thanks thanks