So "ser" and "estar" both mean "to be".Ser should be used when you're talking about an intrinsic quality of something eg. a description, the time, a characteristic of something - Miguel es muy divertido, Ya es las dos de la tarde etc.Estar should be used when you're talking about a mood or something non-permanent eg. location, feelings and moods, and when using the gerund - estoy al lado del parque, estoy enfermo, estoy disfrutando etc.