Off grid generally means that you changed your working grid after laying out your schematic. You can either “Align objects to grid” or change back to the proper grid (which is 50mil). But if you’ve made a bunch of changes in a metric grid and you use the KiCad symbols (that are laid out on a 50mil spacing), you are going to have a lot of work ahead of you.
Align elements to grid is in the context menu, so select the elements with errors, right click and go.
The other bit probably means that you don’t have a PWR_FLAG. This is very common mistake. There’s even a FAQ on this site about it. ErrType(3): Pin connected to some others pins but no pin to drive it