In our organisation we use manually filled in Timesheets.
So we know how long we spend because we track it ourselves whilst we work and enter it into the system. We can then have an overview of it at a later date -- e.g. in Sprint Review / Retrospective.
It feels like there ought to be some sort of technomagic to take this manual stuff away from us, but we haven't been able to identify any way yet.
Our organisation also likes to work with Actuals, and those need a further manual copying across from a to b. Mercifully they recognise that they could not expect us to bookkeep in duplicate, so they have some poor admin person do it for us.
If we could be working smarter instead of harder, do please clue us in!