Net-zero means achieving a balance between the emissions we put into our atmosphere and those taken out. Think of it like a set of scales: producing greenhouse gas emissions tips the scales, and we want to get those scales back into balance, which means no more greenhouse gas can be added to the atmosphere in any given year than is taken out. This state is also referred to as carbon neutral.
To achieve this we need to simultaneously limit the emissions we produce and offset any we do produce by processes that reduce greenhouse gases already in the atmosphere such as carbon sequestration.
‘Zero-emissions’ and ‘zero-carbon’ are slightly different, as they usually mean that no emissions were produced in the first place.