Freedom is related to development. In the opening, it's important to allow the pieces to move freely into the game, facilitating healthy development. When pieces or the central pawns are blocked, it makes it much more difficult to develop properly.
Pieces should also be developed to squares where they have great freedom of movement. A piece that has very limited movement is not much better than one still on its starting square.
A common mistake made by beginners is developing one piece to a square that hinders the development of other pieces. In the above diagram, both players have developed their kingside bishop to the square in front of their d-pawn (d3 for White, d6 for Black). While developing a bishop is a good idea, the placement of these bishops prevents each player from moving their d-pawn, making it more difficult to develop their queenside bishops or gain more control over the center.
In addition, both bishops are now hemmed in somewhat by their own e-pawns, which block their movements along one diagonal. For instance, the White bishop would have been better developed to c4 or e2, where it would have had freedom of movement in two directions. Similarly, the Black bishop would have more freedom on either c5 or e7.
