You create the image of an object, a creature, or some other visible phenomenon that is no larger than a 20-foot Cube. The image appears at a spot that you can see within range and lasts for the duration. It seems real, including sounds, smells, and temperature appropriate to the thing depicted, but it can’t deal damage or cause conditions.
If you are within range of the illusion, you can take a Magic action to cause the image to move to any other spot within range. As the image changes location, you can alter its appearance so that its movements appear natural for the image. For example, if you create an image of a creature and move it, you can alter the image so that it appears to be walking. Similarly, you can cause the illusion to make different sounds at different times, even making it carry on a conversation, for example.
Physical interaction with the image reveals it to be an illusion, for things can pass through it. A creature that takes a Study action to examine the image can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC. If a creature discerns the illusion for what it is, the creature can see through the image, and its other sensory qualities become faint to the creature.
Using a Higher-Level Spell Slot. The spell lasts until dispelled, without requiring Concentration, if cast with a level 4+ spell slot.
* - (a bit of fleece)
The spell isn't dismissed if you cast it again, and you can cast it without concentration and until dispelled with a level 4+ spell slot? So a caster with the spell could feasibly have as many major images as they've had level 4+ spell slots since they've had them, and control it at any time in the future as long as they are within range. A creature with access to this spell and level 4+ slots could create a veritable menagerie of illusions all over the place.