Sharing rules are written to give public read-only access and edit access to some individuals in Salesforce org, like if in any case only managers and superiors are granted extra credentials to your objects as compared to your peers.
These credentials can be Public Read Only or Private. Through sharing rules, we can give more record access to the user. In public groups or through various roles record sharing can be extended through these rules.
These rules are not static and strict for the entire organization. Users are granted greater access through these rules. As far as data access restriction is concerned, we cannot restrict data access through these rules.