When an image has hints to some content, subject or topic but doesn’t directly show them.
If there’s a speech bubble with purple-colored text talking about, like, princess duties, but Twilight Sparkle is not in the image, that’d be
implied twilight sparkle
If a solo picture in which the character is wearing a necklace with some other pony’s cutie mark, there’s a good chance it’s
implied [put shipping tag here]
It can be a bit subjective, sometimes. What in particular were you wondering about?
might be useful, too.