This is the 149th most frequent Turkish word.
olsun
"Let it be" or "may it be."
Here, 'olsun' is used as a wish or a request for someone else to be or do something.
Mutlu olsun, çünkü bu başarıyı hak etti.
Let him/her be happy, because he/she deserved this success.
In this instance, 'olsun' expresses a hope or wish for a condition to be fulfilled.
Yemek güzel olsun, bu akşam misafirimiz var.
May the food be tasty, as we have guests this evening.
Here, 'olsun' is used to express a decision or choice among options.