The Four of Bells is Ether (travel, disappearance/reappearance, vastness, empty space) related to the element Earth (physical items, physical security, the body, worldly beauty). It may represent nothingness: emptiness, open space, silence, blankness, formlessness. It could be a void waiting to be filled, or an empty canvas waiting for an artist's attention. It could also be silence or spaciousness, uncluttered and perhaps liberating, intentionally engineered or accidental.
The Four of Bells may represent minimalism, getting by on the bare necessities in order to be free of the burdens that many possessions bring.
It may also represent an item lost, disappeared into the ether.
In addition to the above, this card may also signify a lack of opposition, or lack of constraint. (Lack of constraint can sometimes lead to chaos, and it may be the case that good constraints are better than none at all. Given considerable freedom, playing it safe, or going with what works, may be a sound course of action.)
The Abstract Four of Bells is abstract Ether (the passing of time, experience in itself, vastness) related to the element Earth (basics, material things, slow moving things). It represents a slowing of things, of life, of phenomena, of pace. Attention-wise, it signifies paying attention to only one or two things at a time, not multitasking, and not being in many places at once, so to speak. Such pace and/or attention may be cultivated purposefully or may come about naturally.
The Abstract Four of Bells may also be symbolic of nurturing patience, the kind which can grow gardens and teach young children, for example. Nurturing patience does not like to rush in with a solution when a solution will not help. Rather, it wants to provide a good foundation for solutions to emerge, and to listen along the way to guide those solutions into fruition. It is at a healthy distance in terms of will, but in terms of attention it is very intimate, picking up on every lead and hint which may prove helpful.