Hi
::)New to the crypto world. which wallet do you recommend for beginners? this for both bitcoins and altcoins? how many wallets should you have to have for tradings?

many thanks
For beginners, i would either recommend you to use Bitcoin Core,
https://bitcoin.org/en/bitcoin-core/ , or even more noob-friendly, Electrum.
https://electrum.org/#homeFor both bitcoin and altcoin, you could try something like Exodus
https://www.exodus.io/releases/how many wallets should you have to have for tradings?

This would depend, you can choose to keep all your altcoin funds in the exchange, which is not so secure, or you can use the wallet specified by the developers of the altcoin. ( If it it isn't support by say Exodus).
Always be wary to check the wallet of viruses, if it is a relatively unknown altcoin. Developers tend to hide them in these files sometimes.
Never use something like blockchain.info, as you will be missing alot of features, including direct access to your private keys, RBF transactions, and CPFP transactions.