"My son is intelligent."
Translation:Mi hijo es inteligente.
Typically "es" denotes permanence or continued quality vs. "está" is temporary or the current state. For example, "eres muy hermosa" and "estás muy hermosa" both means "you are very pretty" but the latter can be construed to actually "estás muy hermosa (hoy/ahora)". This means that if someone "estar" the quality you're describing it means it's a temporary shift from the norm.