Gnosis Chain is an EVM based Ethereum sidechain (L2 chain). Learn more about it here: https://www.gnosischain.com/evm
Please note: Gnosis Chain and Ethereum mainnet are completely separete blockchains. A Safe on Ethereum does not automatically exist on Gnosis Chain. DO NOT SEND ETHEREUM MAINNET FUNDS TO A GNOSIS CHAIN ADDRESS, unless you know what you are doing. Also, dapps are different on both networks. Not all Ethereum mainnet dapps exist on Gnosis Chain and vice versa.
The Gnosis Safe web interface is available for Gnosis Chain at https://gnosis-safe.io/app/gno.
In order to interact with it, you need to connect with a wallet that supports Gnosis Chain.
Metamask does not support Gnosis Chain out of the box. This is how you configure Gnosis Chain on Metamask.
Network name: Gnosis Chain
Chain ID: 100
Block explorer URL: https://blockscout.com/xdai/mainnet/
Hit "save" and select Gnosis Chain in the network dropdown. You should now be able to connect to https://gnosis-safe.io/app/gno with your Metamask.
Metamasks gas estimates are sometimes a bit off on Gnosis Chain. On Gnosis Chain you should be able to use a gas price of 1 in almost all cases.
You can check for other Gnosis Chain compatible wallets here https://developers.gnosischain.com/for-users/wallets