This is the loading screen, at the bottom of the loading screen are 5 status icons. These icons are green if everything is OK but if there is a problem these icons will turn red to help you understand what's wrong. The icons are ordered according to the sequence that Daedalus starts up. When Daedalus starts all the icons will be red but they should change to green as Daedalus progresses through its startup sequence. Normally the 'Node is running' icon on the far left should turn green first, and the 'Node is Syncing' icon on the far right should turn green last. If the first 4 icons are green then the 'Node is syncing' (last Icon).
Daedalus is a full-node wallet. It connects to Cardano network and becomes a part of Cardano network and it downloads and stores a full copy of the blockchain because it is participating in Cardano protocol and independently validating all transactions. For this reason, Daedalus includes Cardano node which runs in the background while Daedalus is running. This is important for maximum security and for fully trustless and fully decentralized operation, without any centrally hosted servers.
'Node is running' icon tells you that the Cardano node is running in the background when it is green. If it is red, the node is not running.
'Node is responding' icon tells you that the Cardano node is responding when it is green. If it is red that means the node is not responding to Daedalus.
'Node is subscribed' icon tells you that the node is connected to Cardano network and subscribed to receive network messages. If it is red that means that Cardano node is not connected and subscribed to the Cardano network and doesn't is not receiving blocks.
'Node time is correct' icon tells you if the local computer time is correct. If it is red that means that the local computer time is not correct.
See Machine clock out of sync with Cardano network for more help if this is red.
'Node is syncing' icon tells you that Cardano node is syncing with the Cardano network. This means that Cardano node is downloading blocks to get a full copy of the blockchain on your local machine. If it is red that means that Cardano node is not syncing. Note that this icon does not indicate that Daedalus is actually in sync, only that synchronisation is in progress.
Daedalus Diagnostics screen
Clicking on any of the icons takes you to the 'Daedalus diagnostics' screen where more diagnostics data is available. If there are issues with connecting to the Cardano network or synchronising with the blockchain some of the items on this screen will be in red color. A screenshot of this screen can be sent to the technical support desk as an attachment when creating a support request ticket.