What is an application for confirmation of a grant in Kenya?

This is an application made by the grantee after the grant of representation is issued. A confirmed grant empowers the executor or administrator to distribute the estate in accordance with the terms of either a will (if the deceased died testate) or rules of intestacy (if the deceased died intestate). The application is made 6 months after the grant or such shorter period as the person holding the grant may suitably determine.

Why and when can someone apply for revocation of certification of a confirmation of grant?

This may be done at any time before or after the grant of representation is confirmed by the court when proceedings to obtain the grant were defective e.g. materially wrong type of petition was filed; the grant was obtained fraudulently etc.

Once a will is probated can it be contested?

Invalid wills or bequests can be contested at any time during probate. The procedure under the law allows for this.