There are 3600 seconds in an hour.
This is a standard conversion factor based on our timekeeping system. Here's a breakdown:

Hours: We divide a day into 24 equal parts, and each part is called an hour.

Minutes: Each hour is further divided into 60 minutes.

Seconds: Each minute is further divided into 60 seconds.
Therefore, to convert hours to seconds, we multiply by the number of seconds per minute (60) and the number of minutes per hour (60):
Seconds per hour = Hours × Minutes/hour × Seconds/minute
1 hour × 60 minutes/hour × 60 seconds/minute = 3600 seconds