What kind of case is this?

[AndreiArgeanu]

My dad has a Samsung s9+ and got this case that is a cover but also is detachable, kind of difficult to explain. Anyone know the name of it or perhaps links to a case like this it would be highly appreciated. 

[dfsdfgfkjsefoiqzemnd]

Looking for a "<your phone type> detachable wallet" will usually yield results. 

or removable wallet, or magnetic wallet.  Plenty of choice really.

 

Here's one example (I'm not the seller, this is merely the first one I came across):

https://www.ebay.com/itm/For-Samsung-Galaxy-S8-S10-Note-8-9-Removable-Leather-Magnetic-Flip-Wallet-Case/192629472702?hash=item2cd99c7dbe:m:meyhgze_dwDZhRDBSscLGwA

 

Some models (like your dad's case) are very basic with merely a couple of card slots and one for notes.  Others are full-on wallets with multiple flaps, zippered compartments for change etc etc.