Don’t understand hard wallet very well.

I am blessed to be sitting on 4 Bitcoin for quite a while that I hold on Coinbase.

I want to gift a very small percent (like .1 ) to my daughters. And I was thinking of doing it with a ledger wallet or something similar.

As I did some research some folks were saying it’s really bad to not have my BTC in storage.

But I don’t quite understand how it works.
Do I keep the Coinbase account but it can only trade if the wallet keys are used?

And if not, how would my daughter trade or sell? Is it because exchanges are not necessary when you have the digital asset in your device??

Sorry if this is too newbie. I’ve read a lot but there is something I’m not getting.