Delegated proof of stake is a consensus mechanism that uses a set amount of nodes for validation, where the amount of nodes is typically low. These validators are voted in by the community as trusted members to represent and run the network.
The biggest benefit of delegate proof of stake is the speed, or TPS. Because there may only be, say, 21 nodes that validate transactions, there are way less nodes that need to perform computations to form consensus. Thus, the blockchain can support dapps that need really high TPS such as social dapps like Musing.