Solubility of NH4Cl at approximately 50.0°C is 50g( 50 g/100 g).
Solubility is the amount of solute dissolved in the solvent. Solute or solvent can be solid liquid or gas.
50 g solubility means 50 g of NH4Cl can be easily dissolved in 100 g of water at 50°C.
Solubility can be increased by increasing temperature of system.