There's not any hidden meaning. "Slid is the past tense form of "slide", a verb that describes moving across a surface with minimal friction. "Under" is a preposition that means "beneath." "Wheel" describes one of the round things upon which cars, trains, bikes, skateboards, etc. move. The definite article "the" tells us that the wheel has been mentioned before or is known to exist from other information that we've been given. If you add a subject it would be a complete sentence.