@Lornakins In the picture you posted of your meter, you are showing a ppm reading. Technically PPM is different from EC; however, there is a formula you can use to convert ppm to EC and vice versa. Most meters will actually do this for you.
PPM which stands for parts per million, is a measurement of the total dissolved solids (TDS) of a solution. Once you add the nutrients to your water, you now have a solution (some growers may refer to this as the soup). Nutrients or fertilizers are made up of salts. So ppm is a measurement of the tds (total dissolved solids or salts) in your solution in terms of parts per million.
The salts or nutrient ions also conduct electrical currents. This means one can estimate the tds of a solution by measuring the electric conductivity of all the charges in the solution. This gives you your EC reading which is typically expressed in terms of microsiemens per centimeter (uS/cm), which when divided by 1000 gives you a reading in terms of milisiemens per centimeter (mS/cm). So a reading of 210 (uS/cm) x10 = 2100 (uS/cm) = 2.1 (mS/cm). and convert that to ppm using a conversion factor (CF). In the US the conversion factor conversion factor = ppm / (ms/cm * 1000)
.50 = 500ppm / (1000us/cm).
So 2.1 (mS/cm) x 1000 = 2100 x .50 = 1050 ppm