Minecraft Bedrock select individual items from stack?

I play Minecraft Bedrock on my cell phone. How can I give my teammate e.g. 10 of them out of a stack of stones?

Only distribute on the cell phone in the inventory until there are 10 stracks

How does this work? The only thing I can do is drop the entire stack by holding down the quick access bar. How can I do other actions and what is the meaning of the green bar if I hold down something in the inventory?

You press the stack and swipe over a few free inventory spaces