That just means that a user can log in to the specified application regardless of if there are IP restrictions on that users Profile. This would make it so they can only access the standard Salesforce site with whatever IP restrictions are in place for the user, but if they go into the Connected App then they can log in from ANY IP.
This only applies to the specific Connected App that you have edited the settings for.
Keep in mind that Connected Apps use OAuth for authentication. Even if you specify to "Enforce IP restrictions" it will only apply for the initial login. After a user is authenticated to a Connected App they can freely switch IP addresses and their authentication will still refresh with OAuth.
I would typically suggest to just relax IP restrictions unless there is a very strict login policy in place with your organization, and if there is such a strict policy then review OAuth to ensure the refresh behavior is not a concern.