The electric field exists in 3-dimensional space.  We only show the field arrows in a plane containing the point charge.   A full 3-dimensional arrow representation of the electric field of of point charges looks messy.
Charge A can be positive or negative and Charge B can be zero, positive or negative.  Both charges can be placed at different positions on the x-axis.
To produce and arrow pointing in the direction of the electric field with a length proportional to the electric field strength at some position, click the position.
The units of charge are 10 nC, the units of distance are m and the units of field strenhth ar N/C.