Liquids are pourable because they do not maintain a "solid" structure as solids do, but still have structure, unlike gasses. Why is this? The forces between liquid particles are weaker than the forces between solid particles. The particles are further apart and move around more easily.
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather