This is the 536th most frequent Swedish word.
gärna
"Gladly," "happily," or "willingly."
Here, 'gärna' expresses a willingness or readiness to assist someone.
Jag hjälper dig gärna.
I am happy to help you.
In this context, 'gärna' conveys a polite suggestion or permission for the listener to take an action.
Du kan gärna sitta där.
You are welcome to sit there.
In this usage, 'gärna' conveys a flexible attitude or willingness to accommodate someone else's preference.