Kubernetes couldn’t pull the image to your nodes.
Click on the workload with the error, and verify the image names under "Configuration"
If the images look right, then your cluster may not be authorized to access the image (see below). If the name is wrong, edit the image: field in your workload's yaml definition, or run kubectl edit <kind>/<name> (e.g. kubectl edit pod/ubuntu) and edit the name inline.
Follow the Kubernetes guide to creating a cluster secret that will allow your cluster to access the image.