I'm using airfoil data that is generated by a program. The generated airfoil has a chord length of 1 unit. I want to know how to scale up this airfoil to required chord length. My airfoil series number 638xx. NACA five digit series.
MountainClimberi is correct. Multiplying both x and y coordinates by the same factor will scale your airfoil correctly. Using a different factor for each will result in a different aspect ratio and a different(stretched) version of that airfoil that will not match its published properties.
Also remember that after scaling the data, your reference location will have moved if it was not (0,0). This may require a translation operation if you need to adjust it.
Per Scaling(geometry) wiki: "The scaling is uniform if and only if the scaling factors are equal (vx = vy = vz)"
Willamate.edu has a good article on 2D transformations including scaling.
Python would be a good language to manipulate this data with. Here is an SE python scaling question.