A liquid is one of the four states of matter. The other three are solids, gases, and plasma. Liquids flow, and they don't have a shape. With no shape, they take shape into the container it is in. For instance, if one pours wine into a wine glass, the wine will shape to fit the glass.
If one pours water into a pitcher, the water will take the shape of the pitcher. Compared to solids, the liquid is weaker. This weakness is why the liquid particles are further apart. When liquids are frozen, they become solids, and when they reach a high boiling point, they become gases.