Your Lead Score baseline settings act as the formula that turns your Contacts' data into actionable lead scores. When you update your baseline settings, the Lead Scores for all of your Contacts will be updated to reflect the new settings. Your Lead Scores are updated near-instantaneously, and can be used immediately after you make your changes.
For more information on what Lead Scoring is, please see this article: What is Lead Scoring?
For more information on how to edit your baseline Lead Score settings, please see this article: How do I assign Lead Scoring points for my Account?