"2009" in Engpsh is simply said as "two thousand nine."
It is formed by saying "two" for the thousands place, "thousand" for the thousands place value and "nine" for the ones place.

The use of "two thousand nine" to refer to the year 2009 is a standard way of expressing years in Engpsh and is commonly used in both spoken and written language.

For example:

"I graduated from college in 2009." (我2009年从大学毕业。)
"The financial crisis of 2008 and 2009 had a significant impact on the global economy." (2008年和2009年的金融危机对全球经济产生了重大影响。)

It's a standard way of counting and expressing the years in Engpsh language and it's widely used across the world.