It's true. Every pawn move creates a weakness. By virtue of how they capture, pawns control two squares. As they move forward, they lose control over the squares they had just controlled. So think twice before moving them!
Pushing pawns is especially dangerous when you do so in front of your king. In the following diagram, black has pushed forward the g-pawn leaving two weaknesses on f6 and h6. White is attempting to take advantage of the weakness on h6 orienting his pawns and pieces towards that square.