You are asking about the mouth.
that would be a volcano
that would be a volcano
vent
It is called Lava.
lava
The stuff that pours out of a volcano is called lava.
This is known as lava.
Lava
The material that erupts from a volcano is called lava. It consists of molten rock that flows out during an eruption.
Magma is called lava once it erupts above ground. Lava is molten rock that flows from a volcano during an eruption.
If you mean 'how does lava release itself from the volcano', it erupts through the volcano's crater. But if you mean 'how does lava erupt from the volcano', then sorry, I have no answers to that.
Lava. Because when magma reaches the surface, it is called lava.