The term tempo rubato means?

The term 'Tempo rubato' means that for some time, until it says 'a tempo', you can expressively quicken or slacken a bit. I think it means mostly to slow down , because I thought rubato was to slow just like ritardando and all that. No. It was 'rebato' I think. Never mind it then. It just means you can quicken or slacken for a bit. Just don't be too lazy.