The current is the flux of the current density j through an area.  The flux of a vector field through an area is the amount of whatever the field represents passing through the area.  Let the current density j be a constant vector field.  The area vector is A = An.  The length of this vector is the size of the area, while its orientation n is perpendicular to the area.  The normal n to the surface can point into two different directions.  We can choose either one of those perpendicular directions.  The flux of the field through the area is I =  j∙A = j A cos(angle), where angle is the angle between the directions of j and A.  The flux can be positive of negative.
If j is measured in C/(m²s) and the sides of the area are measured in m, then the units if the flux are C/s = Ampere (A).  A red box indicates that the flux is positive and a blue box indicates that the flux is negative.