As a Noun:
1. The measure of how heavy something is; the measure of the heaviness of something which is expressed in units such as kilos, pounds, and tonnes. English = weight.
2. A piece of equipment for weighing things, for example for weighing amounts of food that you need in order to make a particular dish. English = scales.
3. A decision about how significant, valuable or useful something is, based on a careful study of its good and bad features. English = evaluation.
As a Verb or Adjective:
1. To measure how heavy something is. English = weigh.
2. To decide how significant, valuable or useful something is, based on a careful study of its good and bad features. English = evaluate. Idiomatic English = weigh up the pros and cons.