Convert Latitude/Longitude values to x,y in Colombia (SouthAmerica)

I don't know any zone 84 (perhaps you meant WGS 84?), but if we look here:

http://www.dmap.co.uk/utmworld.htm

Columbia seems to be centered around UTM zone 18N and 19N.

Which programming language?
To convert Latitude/Longitude to UTM northing/Easting you will need a function like this (C++ language):

#define GRAD_A_RAD(g) ((g)*0.0174532925199433)

bool ConvierteLLaUTM(int Lat, int Long, int *northing, int *easting, int *zona, bool *norte)
{
      const double a  = 6378137.0;
      const double ee = 0.00669437999;
      const double k0 = 0.9996;
      const double e2 = ee / (1-ee);

      double LongTemp = (Long+180)-int((Long+180)/360)*360-180; // -180.00 .. 179.9;
      double LatRad  = GRAD_A_RAD(Lat);
      double LongRad = GRAD_A_RAD(LongTemp);
      double LongOriginRad;

      double N, T, C, A, M;
      
      //Make sure the longitude is between -180.00 .. 179.9
      *zona = int((LongTemp + 180)/6.0) + 1;
      if (Lat >= 56.0 && Lat < 64.0 && LongTemp >= 3.0 && LongTemp < 12.0)
            *zona = 32;

      // Special zones for Svalbard
      if (Lat >= 72.0 && Lat < 84.0) {
            if (LongTemp>=0.0  && LongTemp<9.0)
                  *zona = 31;
            else if (LongTemp>=9.0 && LongTemp<21.0)
                  *zona = 33;
            else if (LongTemp>=21.0 && LongTemp<33.0)
                  *zona = 35;
            else if (LongTemp>=33.0 && LongTemp<42.0)
                  *zona = 37;
      }
      LongOriginRad = GRAD_A_RAD((*zona-1)*6 - 180 + 3);

      N = a/sqrt(1-ee*sin(LatRad)*sin(LatRad));
      T = tan(LatRad)*tan(LatRad);
      C = e2*cos(LatRad)*cos(LatRad);
      A = cos(LatRad)*(LongRad-LongOriginRad);
      M = a*((1 - ee/4 - 3*ee*ee/64 - 5*ee*ee*ee/256)*LatRad
                  - (3*ee/8      + 3*ee*ee/32 + 45*ee*ee*ee/1024)*sin(2*LatRad)
                  + (15*ee*ee/256 + 45*ee*ee*ee/1024)*sin(4*LatRad)
                  - (35*ee*ee*ee/3072)*sin(6*LatRad));
      
      *easting = (int)(double)(k0*N*(A+(1-T+C)*A*A*A/6
                              + (5-18*T+T*T+72*C-58*e2)*A*A*A*A*A/120) + 500000.0);
      *northing = (int)(double)(k0*(M+N*tan(LatRad)*(A*A/2+(5-T+9*C+4*C*C)*A*A*A*A/24
                         + (61-58*T+T*T+600*C-330*e2)*A*A*A*A*A*A/720)));

      if (Lat < 0) {
            *northing += 10000000; //10000000 meter offset for southern hemisphere
            *norte = false;
      } else
            *norte = true;

      return true;
}

Input arguments: (YOU DONT NEED TO KNOW UTM ZONE)
Lat = Latitude in decimal degrees (positive for north hemisphere, negative for south)
Long = Longitude in decimal degrees (negative for west [all Colombia], positive for east)

Output arguments:
northing - northing UTM coordinate (always positive)
easting - easting UTM coordinate (always positive)
zona - UTM zone number
norte - true if north hemisphere