An acknowledgment is a notarial act in which the signer appears before the notary and acknowledges that the signature on the document is theirs and that they signed it willingly.
Depending on applicable law and the certificate wording, the document may already be signed, or the signer may sign in front of the notary. The notary still must identify the signer.
An acknowledgment is not a jurat. A jurat includes a sworn or affirmed statement that the document’s contents are true. If you do not know which act is required, ask the party who requested the notarization.