An evaluation is an appraisal of something to determine its worth or fitness. For example, before you start an exercise program, get a medical evaluation, to make sure you're able to handle the activity.
At the heart of the noun evaluation is the root word value, which means "worth." So an evaluation is an examination to find the worth of something. We do this every day — maybe making an evaluation of the prices in a store to decide whether or not to shop there. We might get an appraisal of our property, which is an evaluation to determine its worth in preparation for taking out a mortgage. Evaluation is vital in planning our lives.