A digital twin is a digital replica of a building or installation, fed with live data from sensors and systems. Where a BIM model mainly describes the design, the digital twin keeps "living" during use.
What you can do
Think of monitoring energy use and indoor climate, predicting maintenance, and simulating scenarios before you intervene physically. This lowers the risk of surprises and extends service life.
The basis
A useful twin starts with good data: a correct as-built model, connected sensors and clear agreements on who maintains what. Start small, with one concrete question, and expand.