>We have named a year to be the time it takes for 1 orbit of the sun.

That is not the case. The year we base our calendar on is the one cycle in the season on earth. You can pick the time between March Equinox and next March Equinox. This is a tropical year

It is it and the average solar day we try to make a calendar from. because there is not an integer fraction between the you need to add leap years

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An obit around the sun relative to a star far away is a sidereal year. It differs from the tropical year by around 20 minutes. It adds up to around 1 day of change in 72 years so not a lot but very relevant if you, for example, do celestial navigation.

Over a long time it has a larger effect, Compare the day that typically zodiac and when the sun really is in the sky, there is a difference of around 20 days because of the 20 minutes difference over more than millennia.