Solvent dissolves solute particles by overcoming the intermolecular forces between the solute (or one can call it the solute-solute interaction). So, to dissolve a solute, the solute-solute interaction must be broken by the solvent particles.

When the temperature increases, the kinetic energy of the solvent particles increases, causing to break the solute-solute interactions more effectively. This allows the addition of more solute particles, as there is space to accommodate more solute particles. So the solubility increases with increase in temperature. Lowering the temperature does the opposite. It decreases the solubility of the solute.