the answer to your question can be in a lot of different ways depending on how much you want to understand the "system". as an end user all you need to know and trust is a trusted and long tested wallet or private key generator that can create random enough keys for you.
some examples of these wallets are: bitcoin core (full node), Electrum (SPV), bitaddress.org (paper wallet), Trezor (hardware wallet).
for more technical understanding try reading the wiki at
https://en.bitcoin.it/wiki/ or developers doc at
https://bitcoin.org/en/developer-documentationBut, once I have a bitcoin it is bound to a private key which is nothing but a big long number but I don’t know how to get at that simple number. All this stuff about seeds for restoration just don’t add up. Just give me the number so I can take it off line and protect it. All these things to scan and wallets to maintain just to deal with a simple number, just a string of digits.
data (a number in this case) can be represented in many forms. for example 2018 is 07E2 in hex or 11111100010 in binary. there is a lot of different ways too. one way that is specific to bitcoin is an alphanumeric encoding excluding 0, O, I, and l characters.
the number:
5500171714335001507730457227127633683517613019341760098818554179534751705629
hex of the same number
0C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D
base58 of the same number which is what you see as your private key in your wallet
5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ
converting between these are also pretty simple, you just have to know the specifications. there are benefits in showing it in base58 format like being more human readable with less errors and the checksum. you can see it here:
https://en.bitcoin.it/wiki/Base58Check_encoding