Command is the modifier. Every combination in the table above uses Command. On Windows in the browser the same actions use Ctrl, and that list has its own page.
Browser conflicts. Some combinations are claimed by the browser before Airtable sees them. Cmd+W closes the tab and Cmd+T opens a new one, so those stay browser actions rather than Airtable ones.
Grid and records. Cell copy, cut, and paste, range selection, and jumping to the edge of a table all work in the browser. Space expands the active record, and Shift+Enter inserts a record below the current cell.
Views and menus. Switching tables, views, and bases and opening the find, filter, sort, and group menus all work from the keyboard. Cmd+/ opens Airtable's own shortcut list inside the app.