Meaning of “reduce” - Learner’s Dictionary

reduce

verb [ T ] uk us /rɪˈdjuːs/

B1 to make something less:

to reduce air pollution
Prices have been reduced by almost 50 percent.
The number of employees was reduced from 500 to 300.

to add one or more electrons to a substance or to remove oxygen from a substance

(Definition of “reduce” from the Cambridge Learner’s Dictionary © Cambridge University Press)