A year is measured as the amount of time it takes Earth to orbit the sun once, a galactic year is the time it takes our sun to make one full orbit of the center of the galaxy.
In galactic years, how old is our sun?
According to the blog How old is the Sun in Galactic years? (Siegel, 2008), a Galactic year is about 223 million Earth years.
The age of the Sun, according to the Stanford Solar Centre's page How old is the Sun? is approximately 4.57 billion years.
This would put the sun at approximately 20.5 galactic years old.