I am just wondering what are the methods which can hide all the transactions and also able to validate transactions in an block chain? I am new to block chain and was looking at how block chain work mainly proof of stake based . They check validity by going through all the transactions which is something concerning as everyone can see the transactions. So what are ways to hide all transactions and also make everyone able to check validity of new block.
This question is not only for block chain relm but also for cryptography.
So what are ways to hide all transactions


In the blockchain used by Bitcoin it is not ever possible to hide transaction details because the integrity of the whole system depends on those being public.

However the sensitive parts of those details are mostly Bitcoin-addresses and amounts. There is a privacy issue if observers can infer information by comparing use of the same address across multiple transactions.

This is why Bitcoin (for example) is often described as not anonymous but as psedonymous. You can't see people's names in transaction data but you can see the Bitcoin-addresses.

Generally people hide their identity by 


never re-using Bitcoin-addresses and by 
using coin tumblers.


This makes it very very difficult for third-party observers to associate a transaction with a specific person.