With the Score voting type of voting, you can set multiple criteria for the assigned evaluators to evaluate shortlisted submissions. Setting the weight of a criteria means you to set how much it contributes to the total score of a submission for the voting round.
The best way to understand how these weights work is by thinking of them as a percentage distribution towards the total score and making sure the sum of the weights across all criteria is 100.
Some quick examples
Example A: You have 2 criteria that judges will use to evaluate submissions for your program. If both criteria have equal importance, you can set a weight of 50 for each, meaning each would contribute 50% of the total score of the submissions.
Example B: You have 3 criteria that judges will use to score program submissions. The weights of the 3 criteria can be set to 60, 20, and 20, where 60 is the weight of the key criteria, and 20 is the weight of the other 2 less important criteria.