Once again, your point of reference is a “year,” which is actually an event: the earth making one trip around the sun.
The second is the SI base unit of time, commonly understood and historically defined as 1/86400th of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each.
Another intuitive understanding is that it is about the time between beats of a human heart.[nb 1]
Mechanical and electric clocks and watches usually have a face with 60 tickmarks representing seconds and minutes, traversed by a second hand and minute hand.
Digital clocks and watches often have a two-digit counter that cycles through seconds.
In common parlance, a “clock tick” is a second, though most modern clocks are digital electronic, and do not actually tick.[citation needed]
The second is also part of several other units of measurement like velocity, acceleration, and frequency.
Though the historical definition of the unit was based upon this division of the Earth’s rotation cycle, the formal definition in the International System of Units (SI) is a much steadier timekeeper: 1 second is defined to be exactly 9,192,631,770 cycles of a Caesium atomic clock.[1][2][3]
Because the Earth’s rotation varies and is also slowing ever so slightly, a leap second is added to clock time[nb 2] to keep clocks in sync with Earth’s rotation.
one year = 364.25 x 24 x 60 x 60 = 31,536,000 seconds
“the formal definition in the International System of Units (SI):
1 second is defined to be exactly 9,192,631,770 cycles of a Caesium atomic clock.[1][2][3]”