travel from Copenhagen to Agerskov

Agerskov as the inland small town in Southern Jutland?

I don't know what the "best" way is for you. But I think it's most likely one of these two options:

Public transport: A few variations of train + bus. Check journeyplanner.dk for your options. Buy tickets on dsb.dk/en or in DSB's app. A seat reservation cost 30 DKK and is something I would highly recommend.

Drive: Rent a car and get behind the wheel. It's fairly straight forward, most of it on motorways. Note the road toll on the Great Belt Bridge https://storebaelt.dk/en/prices-and-discounts/private/

Or, combine the options and take the train to e.g. Rødekro, Vojens or maybe Kolding and rent a car there.