Our year is actually has how many days?

A solar year (tropical year) is approximately 365.2422 days. This is why we add a leap day every 4 years (0.25 extra day), but skip it on century years not divisible by 400, because 0.2422 is slightly less than 0.25. This precise measurement is based on astronomical observations of Earth's orbit around the Sun. The other values are either too high or don't match actual astronomical measurements.