it inecreases the absolute amount of the Net Exports number and makes it less negative.
Allow me to correct your correction. A negative NX means that it (net exports is negative, i.e., in the red) is a reduction from GDP Imports...it is subtracted from the GDP. Manciwics...your source...concludes as an axiomatic matter...that trade deficits are not a 'win' for the economy. The imports are subtracted from GDP. Adversely effecting savings of capital. Etc. They are a loss.