To make sure your project fits into your actual apartment, and if you can squeeze between all the stylish items you’ve put around your house, you will need to measure the distance between objects. That’s when a Ruler comes in handy.
Click on the Settings (gear icon) -> Ruler in the menu to summon it. It’ll appear in your project. Now you can measure the distance between objects by placing a ruler between them.
Note: if you can't find the Ruler, make sure you're in 2D mode. You can only use the Ruler in 2D at the moment.