The unit of rate of reaction is

The definition of the rate of reaction is the rate at which the reactant dissipates over time per unit or the pace at which the product manifests over time per unit.
Think about the reaction A+B+C.
The reaction will occur at the following rate:
Rate: $=-\frac{\delta A}{\delta \mathrm{T}}=\frac{\delta \mathrm{B}}{\delta \mathrm{T}}=\frac{\delta \mathrm{C}}{\delta \mathrm{T}}$
As the ratio of concentration to time is concerned, the unit of concentration is the mole per litre and the unit of time is the second.
The rate of reaction is measured in ${\mathrm{moleL}}^{-1}{\sec }^{-1}$.