First important point about Agile and Scrum is, they both complement each other. Agile is bigger picture and Scrum is one part that is one flavour of it.
Scrum is one of the Agile follower. Agile have many more flavours like Extreme programming, Lean, Kanban, Crystal. Scrum is one of it and famous to be one of the lightweight agile framework. Due to its lightweight nature Scrum is very popular. It's believed that Scrum is easy to implement and follow. As said earlier, this makes Scrum one of the Agile Flavour
Agile is based on iterative and incremental development which is implemented in Scrum by its methodology of roles, ceremonies and artefacts. Agile also emphasis on time-boxing which is implemented in scrum beautifully by fixing times of its Sprints and Ceremonies. All the events/ceremonies in Scrum are having fixed durations which is recommended for one month of Sprint. Same can be adjusted for any increase or decrease. We shall discuss all those events in detail during this course. Scrum events are checkpoints for adaptation. Agile talks about adaptation and Scrum implements it daily (Daily Scrum), End of Sprint (Sprint review), before next Sprint (Sprint Retrospective/planning) meetings
In nutshell, Scrum is one implementer of agile methodology and used widespread due to its ease of implementation