What is happening is that the competing network is allowed to show a game in the time slot while the home team plays. IOW, if the Bills were to host New England at 1 PM, the other network (most likely FOX) would not be allowed to show a game in that same time slot in the past. Now they can, in most cases, for this year only. This is a 1-year experiment by the NFL.
In the time slot the home team is not playing, say 4 PM in the example above, both networks could, and still can, show games. So each area is supposed to get 3 games between the 1 PM and 4 PM times slots; however, sometimes in the past, they only got 2 games, due to the restriction above. Now that restriction is lifted, for this year only.
The exception is that twice a year for this year, home teams are allowed to prevent the competing network from airing a game in their time slot. After two times though, they cannot demand such a limit.
See my post above.