According to our current understanding of physics, there is no universally accepted "Planck length" for the time dimension similar to the Planck length that exists for the spatial dimensions. The Planck length, denoted by "ℓP," is a fundamental constant derived from the combination of fundamental constants such as the speed of light, Planck's constant, and the gravitational constant. It represents the scale at which the effects of quantum gravity are expected to become significant.
In the context of the Planck length, one might expect a corresponding "Planck time" that represents the smallest meaningful interval of time. However, the notion of a Planck time is somewhat ambiguous and lacks definitive physical significance at present. The reason is that the unification of quantum mechanics and general relativity, which would be required to understand the behavior of spacetime at extremely small scales, is still an ongoing challenge in theoretical physics.
That said, the Planck time, denoted by "tP," can be defined by dividing the Planck length by the speed of light (tP = ℓP/c). This yields a value of approximately 5.39 x 10^(-44) seconds. The Planck time represents a rough estimation of the order of magnitude at which time intervals might lose their meaning in our current understanding of physics. However, it is important to note that this value does not hold any fundamental physical significance and should not be interpreted as an absolute limit or a smallest meaningful unit of time.
It is worth mentioning that theories attempting to reconcile quantum mechanics and general relativity, such as certain approaches to quantum gravity or string theory, propose potential modifications to our understanding of spacetime at extremely small scales. These theories might offer insights into the behavior of time or suggest a fundamental limit for time intervals. However, such ideas are still speculative and the subject of ongoing research and debate in the field of theoretical physics.