SegWit is a solution to increase the scalability of blockchain and has already been successfully implemented on Litecoin and Bitcoin.
Currently, every block not only record every transaction details, it also includes details such as the timestamp, Bitcoins transferred, or the transaction’s digital signature, to verify the legitimacy of each transaction.
Digital signatures are required for verification when miners process transactions, before adding the transaction to the block.
However, to the regular user, he is only concerned with how much assets he has in his accounts, not verifying every transaction. Segwit removes the digital signature information within a block, allowing each block to hold more transactions, achieving the goal of scalability.