Grab is the default mode selected when you first load into a creation session. Its icon is a little grabby hand in the top tool bar, found just right of the Asset Browser.
To use Grab, simply click and drag an entity to the place you want to move it. It allows you to move the object freely; if you need more precise directional control while moving objects, check out the Transform Manipulator.
Moving objects with Grab manipulator functions exactly the same as using the baseline sphere with the Transform Move tool.
Objects moved with Grab manipulator will collide and snap to nearby voxels in the scene. Objects with flatter surfaces, like walls and floors, are easiest to use this function on. When no snappable voxels are nearby, the selected object will not snap to anything and instead be placed mid air a set distance from camera.
Voxel snapping from the top of one floor level to another