If before expiry of period of limitation, an acknowledgement in writing is made about liability of debt and promised to pay. What will be the effect of such acknowledgement?

Section 18 of Limitation Act: Effect of acknowledgment in writing—(1) Where, before the expiration of the prescribed period for a suit of application in respect of any property or right, an acknowledgment of liability in respect of such property or right has been made in writing signed by the party against whom such property or right is claimed, or by any person through whom he derives his title or liability, a fresh period of limitation shall be computed from the time when the acknowledgment was so signed