The Avalanche network is a Ethereum Virtual Machine Compatible Layer 1 blockchain that allows anyone to deploy smart contracts and build dapps (decentralized applications) on top of it.
Also known as the AVAX network, it uses the AVAX token as payment for network costs. You can explore transactions done on the Avalanche network using snowtrace.io.
The Uniswap web app now supports the Avalanche Network. This means anyone can swap and provide liquidity using the Uniswap Protocol on the Avalanche Network.
Learn more about this in these Uniswap Help Center articles: